ANDROID: GKI: regmap: Add regmap vendor hook for of_syscon_register

For global registers access, UNISOC have one special method called set/clear
mechanism that would avoid using hardware spinlock. But now regmap framework
does not support our set/clear mechanism, so add vendor hook to support
this feature.

Bug: 228907258
Signed-off-by: Xiaopeng Bai <xiaopeng.bai@unisoc.com>
Change-Id: I9a6651f07a048ffebd5c2d8e369a4e7b374bc182
(cherry picked from commit 53e342c1)