regulator: msm-gfx-ldo: Update the LDO handling sequence

Fix the LDO configuration and voltage update sequence.
While at it, add additional debug logging.

Change-Id: I15dbbfdf18e8694920f1344cfcd3176ffa0f7c3e
Signed-off-by: Anirudh Ghayal <aghayal@codeaurora.org>