media: dvb: Add events API for demux

user-space programs using demux require to be notified
on several kinds of events such new PES event,
new section event, new recording-chunk event and
other error events. demux API was extended to meet
this requirement

Change-Id: I768b6acde346139e194a3e6637b6fc0fc9648446
Signed-off-by: Hamad Kadmany <hkadmany@codeaurora.org>