mfd: si476x-cmd: Add missing colon(s) for all documented kerneldoc arguments

Kerneldoc validation gets confused if syntax isn't "@.*: ".

Adding the missing colons squashes the following W=1 warnings:

 drivers/mfd/si476x-cmd.c:525: warning: Function parameter or member 'dout' not described in 'si476x_core_cmd_dig_audio_pin_c
 drivers/mfd/si476x-cmd.c:525: warning: Function parameter or member 'xout' not described in 'si476x_core_cmd_dig_audio_pin_c
 drivers/mfd/si476x-cmd.c:574: warning: Function parameter or member 'core' not described in 'si476x_core_cmd_zif_pin_cfg'
 drivers/mfd/si476x-cmd.c:574: warning: Function parameter or member 'iqclk' not described in 'si476x_core_cmd_zif_pin_cfg'
 drivers/mfd/si476x-cmd.c:574: warning: Function parameter or member 'iqfs' not described in 'si476x_core_cmd_zif_pin_cfg'
 drivers/mfd/si476x-cmd.c:574: warning: Function parameter or member 'iout' not described in 'si476x_core_cmd_zif_pin_cfg'
 drivers/mfd/si476x-cmd.c:574: warning: Function parameter or member 'qout' not described in 'si476x_core_cmd_zif_pin_cfg'
 drivers/mfd/si476x-i2c.c:550: warning: Function parameter or member 'func' not described in 'si476x_core_fwver_to_revision'
 drivers/mfd/si476x-cmd.c:631: warning: Function parameter or member 'core' not described in 'si476x_core_cmd_ic_link_gpo_ctl
 drivers/mfd/si476x-cmd.c:631: warning: Function parameter or member 'icin' not described in 'si476x_core_cmd_ic_link_gpo_ctl
 drivers/mfd/si476x-cmd.c:631: warning: Function parameter or member 'icip' not described in 'si476x_core_cmd_ic_link_gpo_ctl
 drivers/mfd/si476x-cmd.c:631: warning: Function parameter or member 'icon' not described in 'si476x_core_cmd_ic_link_gpo_ctl
 drivers/mfd/si476x-cmd.c:631: warning: Function parameter or member 'icop' not described in 'si476x_core_cmd_ic_link_gpo_ctl
 drivers/mfd/si476x-cmd.c:662: warning: Function parameter or member 'core' not described in 'si476x_core_cmd_ana_audio_pin_c
 drivers/mfd/si476x-cmd.c:662: warning: Function parameter or member 'lrout' not described in 'si476x_core_cmd_ana_audio_pin_
 drivers/mfd/si476x-cmd.c:697: warning: Function parameter or member 'core' not described in 'si476x_core_cmd_intb_pin_cfg_a1
 drivers/mfd/si476x-cmd.c:697: warning: Function parameter or member 'intb' not described in 'si476x_core_cmd_intb_pin_cfg_a1
 drivers/mfd/si476x-cmd.c:697: warning: Function parameter or member 'a1' not described in 'si476x_core_cmd_intb_pin_cfg_a10'
 drivers/mfd/si476x-cmd.c:746: warning: Function parameter or member 'core' not described in 'si476x_core_cmd_am_rsq_status'
 drivers/mfd/si476x-cmd.c:746: warning: Function parameter or member 'rsqargs' not described in 'si476x_core_cmd_am_rsq_statu
 drivers/mfd/si476x-cmd.c:746: warning: Function parameter or member 'report' not described in 'si476x_core_cmd_am_rsq_status
 drivers/mfd/si476x-cmd.c:878: warning: Function parameter or member 'core' not described in 'si476x_core_cmd_fm_seek_start'
 drivers/mfd/si476x-cmd.c:878: warning: Function parameter or member 'seekup' not described in 'si476x_core_cmd_fm_seek_start
 drivers/mfd/si476x-cmd.c:878: warning: Function parameter or member 'wrap' not described in 'si476x_core_cmd_fm_seek_start'
 drivers/mfd/si476x-cmd.c:907: warning: Function parameter or member 'core' not described in 'si476x_core_cmd_fm_rds_status'
 drivers/mfd/si476x-cmd.c:907: warning: Function parameter or member 'status_only' not described in 'si476x_core_cmd_fm_rds_s
 drivers/mfd/si476x-cmd.c:907: warning: Function parameter or member 'mtfifo' not described in 'si476x_core_cmd_fm_rds_status
 drivers/mfd/si476x-cmd.c:907: warning: Function parameter or member 'intack' not described in 'si476x_core_cmd_fm_rds_status
 drivers/mfd/si476x-cmd.c:907: warning: Function parameter or member 'report' not described in 'si476x_core_cmd_fm_rds_status
 drivers/mfd/si476x-cmd.c:1052: warning: Function parameter or member 'core' not described in 'si476x_core_cmd_am_seek_start'
 drivers/mfd/si476x-cmd.c:1052: warning: Function parameter or member 'seekup' not described in 'si476x_core_cmd_am_seek_star
 drivers/mfd/si476x-cmd.c:1052: warning: Function parameter or member 'wrap' not described in 'si476x_core_cmd_am_seek_start'

Cc: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>