media: videodev2.h: add V4L2_FMT_FLAG_CONTINUOUS_BYTESTREAM

Add an enum_fmt format flag to specifically tag coded formats where
full bytestream parsing is supported by the device.

Some stateful decoders are capable of fully parsing a bytestream,
but others require that userspace pre-parses the bytestream into
frames or fields (see the corresponding pixelformat descriptions
for details).

If this flag is set, then this pre-parsing step is not required
(but still possible, of course).

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Reviewed-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Reviewed-by: Alexandre Courbot <acourbot@chromium.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>