drm/msm/sde: reset plane state if not used in first commit

For planes attached in continuous splash, if client is not reading
the plane state and neither disabled the plane leads to stale
plane state and it can cause atomic check failures as there is no
valid fb attached. This change reset the plane state of the planes
used in continuous splash during continuous splash handoff only if
client is not using the plane in the current commit.

Change-Id: Ia2ddf1f1d3ca6b3f4660e80c88d5acf97897b0c7
Signed-off-by: Prabhanjan Kandula <pkandula@codeaurora.org>