disp: msm: sde: avoid using spinlock for register log

Add support to use atomic variable instead of spinlock
for register logs during register write. This change
helps in reducing the run-time and is safe to use as
most of the register writes happen in commit context.

Change-Id: Ib7e377f80cbf437e391792b0b424cbd1eefdf497
Signed-off-by: Yashwanth <yvulapu@codeaurora.org>