V4L/DVB (10575): V4L2: Add COLORFX user control

This is a common feature on many cameras. the options are:
Default colors,
B & W,
Sepia

Signed-off-by: Sergio Aguirre <saaguirre@ti.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>