V4L/DVB: core: add support for more color effects

Add support for more color effects (negative, sketch, emboss, etc) by
extending the  v4l2_colorfx enum items.

Signed-off-by: Xiaolin Zhang <xiaolin.zhang@intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>