media: dvb: dvb-core: Fix wrong check of continuity-counter

Continuity-counter is compared for each packet against the
counter of the previous packet. This check should take
into account the very first packet after feed is started
otherwise the first packet might be wrongly dropped.

Change-Id: Ibe31bad3eccbd4b6ed1f4b0df1049e28399493d6
Signed-off-by: Hamad Kadmany <hkadmany@codeaurora.org>