V4L/DVB (4921): Budget-av, budget-ci: Fix MC1 register programming

Remove bogus read during MC1 programming.
A '1' bit could never be cleared using the old code.
Use MASK_xx macros.

Signed-off-by: Hartmut Birr <e9hack@gmail.com>
Signed-off-by: Oliver Endriss <o.endriss@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>