[media] em28xx: VIDIOC_G_TUNER: remove unneeded setting of tuner type

The tuner type is set by the v4l2-core based on the device type.

Signed-off-by: Frank Schäfer <fschaefer.oss@googlemail.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>