media: amphion: only insert the first sequence startcode for vc1l format

For format V4L2_PIX_FMT_VC1_ANNEX_L,
the amphion vpu requires driver to help insert some custom startcode
before sequence and frame.
but only the first sequence startcode is needed,
the extra startcode will cause decoding error.
So after seek, we don't need to insert the sequence startcode.

In other words, for V4L2_PIX_FMT_VC1_ANNEX_L,
the vpu doesn't support dynamic resolution change.

Fixes: 145e9363 ("media: amphion: implement malone decoder rpc interface")
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>