[media] dmxdev: Fix a compilation warning due to a bad type

drivers/media/dvb/dvb-core/dmxdev.c: In function ‘dvb_dmxdev_start_feed’:
drivers/media/dvb/dvb-core/dmxdev.c:583:13: warning: comparison between ‘enum dmx_ts_pes’ and ‘enum <anonymous>’

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>