msm: media: Update venus buffer size calculation for RGBA UBWC format

Remove VENUS_EXTRADATA_SIZE of 8K in venus buffer size calulcation
for RGBA and RGBA UBWC color formats.
Without this change gralloc allocates less output buffer size
as it doesn't account for extradata size causing qbuf failure
in v4l2 framework.

Change-Id: Iddd93aa4d0aaba3e404c41c3200a2b444071b7f5
Signed-off-by: Sowmya Pandiri <spandiri@codeaurora.org>