Explicitly configure the IR Tx and IR Rx pins to be driven by the
IR Rx and Tx pads from the AV core for CX23888 IR.

For the HVR-1850 and HVR-1290 configure the IR Tx level inversion,
so the Tx LED is off when idle.
Signed-off-by: Andy Walls <awalls@md.metrocast.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>