[media] tuner-xc2028.c: fix compile warning

drivers/media/common/tuners/tuner-xc2028.c: In function 'generic_set_freq':
drivers/media/common/tuners/tuner-xc2028.c:936:15: warning: comparison between 'enum tuner_mode' and 'enum v4l2_tuner_type'

Argument type was enum tuner_mode, but should have been enum v4l2_tuner_type.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>