msm: vidc: Make vmem a mandatory resource for video

Video encoder's behavior without vmem is undefined and
vmem is recommended to meet decoder performance as well
so make vmem a mandatory resource for video. If vmem
allocation fails then video playback will be aborted.

Change-Id: I98a7ad84161b077758713e078332218f30ffffca
Signed-off-by: Vinay Kalia <vkalia@codeaurora.org>