V4L/DVB (12512): ov772x: implement a band-stop filter support

The V4L2_CID_BAND_STOP_FILTER control is used to switch the "Banding Filter" on
OV772x cameras on and off and to set the minimum AEC value in BDBASE register.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>