media: dvb: Add detection of SEI messages

Video decoder expects SEI messages to be sent along
with the data of the following frame instead of the
preceding frame.

Detection of SEI messages allows closure of previous
frame data when SEI messages are encountered.

Change-Id: I43a292c4518592d45373c63eb8f2edae14b3adcd
Signed-off-by: Hamad Kadmany <hkadmany@codeaurora.org>