V4L/DVB: cx23885: Add preliminary IR Rx support for the HVR-1250 and TeVii S470

Add initial IR Rx support using the intergrated IR controller in the
A/V core of the CX23885 bridge chip.

This initial support is flawed in that I2C transactions should not
be performed in a hard irq context.  That will be fixed in a
follow on patch.

The TeVii S470 support is reported to generate perptual interrupts
that renders a user' system nearly unusable.  The TeVii S470 IR
will be disabled by default in a follow on patch.

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