disp: msm: sde: add 3d_merge_reset property for lagoon

Add changes to update the WB disable CTL sequence
for lagoon by enabling 3d_merge_reset property.
WB disable sequence without enabling this property is not
fully disabling WB engine and causing underruns
on external display when WB CTL is reused for
external display.

Change-Id: I6a342af4a6283d4ac6a02ae83385584f355b0080
Signed-off-by: Jayaprakash <jmadiset@codeaurora.org>