msm: vidc: Updating H264 decoder internal buffer size calculation

For H264 decoder, resolutions with non-multiple of 16 were
calculating less internal buffer size. Updated calculation
to handle such scenarios.

Change-Id: I3c07b843cc898a584aba4c9f26627898a7427fe8
Signed-off-by: Shivendra Kakrania <shiven@codeaurora.org>