V4L/DVB (3435): Remove 'pid' from struct dmxdev_filter

The PID value is already stored in struct dmx_sct_filter_params which is
a member of struct dmxdev_filter.
Acked-by: Johannes Stezenbach <js@linuxtv.org>

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