[media] v4l2: remove obsolete v4l2_chip_match_host()

This function is no longer needed since it is now the responsibility of the
v4l2 core to check if the DBG_G/S_REGISTER and DBG_G_CHIP_INFO ioctls are
called for the bridge driver or not.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>