media: venus: helpers: Calculate properly compressed buffer size

For resolutions below 720p the size of the compressed buffer must
be bigger. Correct this by checking the resolution when calculating
buffer size and multiply by eight.

Signed-off-by: Stanimir Varbanov <stanimir.varbanov@linaro.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>