st/va: pass picture desc to begin and decode

At least vl_mpeg12_decoder uses the picture
desc in begin_frame and decode_bitstream.

https://bugs.freedesktop.org/show_bug.cgi?id=92634

Signed-off-by: Julien Isorce <j.isorce@samsung.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
1 file changed