[media] rtl2832: save some data space by using a macro instead of a table

Instead of using a table for reg bitmask, use a macro. This should save
some data segment space.

Cc: Thomas Mair <thomas.mair86@googlemail.com>
Cc: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>