drm/msm/sde: ignore last close during cont splash

Ignore last close call to msm when continuous splash is
still ON. This is to avoid cleaning up the states when
we did not receive first commit.

Change-Id: Ide8df725415d0ff15159be01790535b8a8ab0dfc
Signed-off-by: Kalyan Thota <kalyant@codeaurora.org>