msm_fb: Update MDP fence wait behaviour

The current fence wait times out too early in cases where the GPU
is under a heavy workload. Change this behaviour to warn and wait
for a longer time for GPU to complete it's work.

Change-Id: I8b20c22733a77c1aaea4a1fd1e4daaa14b5ec2fd
Signed-off-by: Naseer Ahmed <naseer@codeaurora.org>

Conflicts:
	drivers/video/msm/msm_fb.c