[media] sn9c20x: fix checkpatch warning: sizeof cmatrix should be sizeof(cmatrix)

Signed-off-by: Morgan Phillips <winter2718@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>