mfd: rtsx: Prevent 'used uninitialised' warnings

drivers/mfd/rtl8411.c: In function 'rtl8411_fetch_vendor_settings':
drivers/mfd/rtl8411.c:58:7: warning: 'reg1' is used uninitialized in this function [-Wuninitialized]
drivers/mfd/rtl8411.c: In function 'rtl8411b_fetch_vendor_settings':
drivers/mfd/rtl8411.c:79:7: warning: 'reg' is used uninitialized in this function [-Wuninitialized]
drivers/mfd/rtl8411.c: In function 'rtl8411_fetch_vendor_settings':
drivers/mfd/rtl8411.c:69:26: warning: 'reg3' may be used uninitialized in this function [-Wuninitialized]

Tested-by: Micky Ching <micky_ching@realsil.com.cn>
Signed-off-by: Lee Jones <lee.jones@linaro.org>