V4L/DVB (13096): v4l2-subdev: Add v4l2_subdev_ir_ops and IR notify defines for v4l2_device

Add v4l2_subdev_ir_ops and IR notify defines for v4l2_device.  This change
is specifically needed at this time to support the integrated IR controller in
the CX2388[58] chips.

Signed-off-by: Andy Walls <awalls@radix.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>