drm/msm/dsi-staging: ignore panel disable failure

When DSI controller is in bad state, sending panel off commands
cannot be guranteed. The DSI controller goes for a complete reset
during display enable. Thus, ignore failures while sending panel off
commands during display disable.

Change-Id: Ibe1f551e43de2a7981adb8ac59a60dd26225edff
Signed-off-by: Shashank Babu Chinta Venkata <sbchin@codeaurora.org>