[media] saa6752hs: drop compat control code

The saa7134 driver is now converted to the control framework, so drop the
control compat code in saa6752hs.c.

Also add 'const' to several static arrays.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>