saradc: s1a: support saradc/keypad [1/1]

PD#SWPL-134719

Problem:
S1A Silicon Bringup.

Solution:
S1A and TXHD2 have the same controller.

Verify:
S1A/BG201

Change-Id: I0ba70fec066202fc13559caee670da30721feaa8
Signed-off-by: Huqiang Qin <huqiang.qin@amlogic.com>
6 files changed