V4L/DVB (12276): Remove a useless check from dvb_dmx_swfilter_packet()

Values for 'pid' range from 0 to 0x1fff. Therefore 'feed->pid' can never
be equal to both 'pid' and 0x2000. This makes the continue statement have
no effect.

Signed-off-by: Andreas Oberritter <obi@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>