regulator: Add snapshot of MSM GFX LDO driver

This is a snapshot of MSM GFX LDO regulator driver for SDM660 as of
msm-4.4 'commit ae5acb1 (Merge "soc: msm-pcm: Add mutex lock to protect
prvt data")'.

Change-Id: Id13b6b601c91aa6c2c2f0e6d820a244144b60437
Signed-off-by: Anirudh Ghayal <aghayal@codeaurora.org>
Signed-off-by: Asha Magadi Venkateshamurthy <amagad@codeaurora.org>