video: msm: Increase video encoding output buffer size

When bistream buffer size is half of YUV buffer size, video core
may be put into a bad state where output buffers are not returned
back to user space. Increasing the output buffer size solves the issue.

Signed-off-by: Shuzhen Wang <shuzhenw@codeaurora.org>

Change-Id: I25a89a838e35207a8cbb6b2bda3472c3a00bac17