fbdev: msm: check for panel status before waiting for pp done

Panel may go bad during esd test, in such cases do not wait
for PP done when switching from ON to LP1/LP2, which will cause
fifo error's and black screen.

Change-Id: I2a416e2a5e332f0be00215734342405292410c41
Signed-off-by: Raghavendra Ambadas <rambad@codeaurora.org>