mfd: rtsx: Add support for rts522A

rts522a(rts5227s) is derived from rts5227, and mainly same with rts5227.
Add it to file mfd/rts5227.c to support this chip.

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