media: venus: vdec: handle 10bit bitstreams

Handle 10bit video streams in the decoder by using dithering, i.e
the decoder output buffers will be in 8bit format.

The runtime handling is implemented by sending v4l2 event to
userspace application, then the application should stop the
streaming on capture queue and initiate format negotiation, and
start streaming again.

Signed-off-by: Aniket Masule <amasule@codeaurora.org>
Co-developed-by: Stanimir Varbanov <stanimir.varbanov@linaro.org>
Signed-off-by: Stanimir Varbanov <stanimir.varbanov@linaro.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>