media: amphion: support to decode RealVideo video

amphion decoder add support for the RealVideo video.
RV30 and RV40 are support by amphion decoder.

Signed-off-by: Ming Qian <ming.qian@nxp.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>