drm/msm/sde: Update LUT dma under-run handling

LUT dma under-run is a recoverable error, remove the panic and add a
event log to capture status.

Change-Id: If29d7b74a57527d09d084112276545e93c570571
Signed-off-by: Raviteja Tamatam <travitej@codeaurora.org>