media: dvb: Fix pull mode for section filter

Processing TS packet data in the section pipe does not consume all
the packets if it needs to stall while in pull mode.
Section pipe handler did not continue from the same point where it
left as it should and whether or not new data comes in after stalling.

Change-Id: I4e4c9644531814745449033e082c929ea0e28c79
Signed-off-by: Gilad Broner <gbroner@codeaurora.org>