disp: msm: sde: add optional sde register writes in event logs

Add changes to configure register writes in the event
log dump. The register writes can be enabled in the dump
through the debug_fs command.

Change-Id: I08154e193f670999746fbb30291a866db85c8c8d
Signed-off-by: Jayaprakash <jmadiset@codeaurora.org>