msm: vidc: Fix buffer size calculation

Fix buffer size calculation for NV12, NV21 and UBWC color format to
accommodate last row buffers for any frame whose size is not a
multiple of 512x512.

Change-Id: I97c7e01b10cfce90203c3babcdeb6513d0003d34
Signed-off-by: Amit Shekhar <ashekhar@codeaurora.org>