media: mt9p031: Use BIT macro

Make use of the BIT macro for setting individual bits. This improves
readability and safety with respect to shifts.

When on it also remove two zero value disable defines.

Signed-off-by: Stefan Riedmueller <s.riedmueller@phytec.de>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>