media: venus: vdec: allow bigger sizeimage set by clients

In most of the cases the client will know better what could be
the maximum size for compressed data buffers. Change the driver
to permit the user to set bigger size for the compressed buffer
but make reasonable sanitation.

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