i2c: designware: Fix the kernel doc description for struct dw_i2c_dev

$ scripts/kernel-doc -none drivers/i2c/busses/i2c-designware-core.h
warning: Function parameter or member 'rst' not described in 'dw_i2c_dev'
warning: Function parameter or member 'get_clk_rate_khz' not described in 'dw_i2c_dev'
warning: Function parameter or member 'flags' not described in 'dw_i2c_dev'
warning: Function parameter or member 'functionality' not described in 'dw_i2c_dev'
warning: Function parameter or member 'master_cfg' not described in 'dw_i2c_dev'
warning: Function parameter or member 'set_sda_hold_time' not described in 'dw_i2c_dev'
warning: Function parameter or member 'rinfo' not described in 'dw_i2c_dev'

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Acked-by: Randy Dunlap <rdunla@infradead.org>
Signed-off-by: Wolfram Sang <wsa@kernel.org>