[media] gspca_pac73xx: Remove comments from before the 7302 / 7311 separation

The pac7302 and pac7311 driver still contains some comments from before
they were separated, such as marking certain functions 7302 or 7311 only,
with the new split drivers these make no sense, remove them.

Also removed the empty/unused sd_stop0 function from pac7311.c

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>