V4L/DVB: cx25840: Add support for CX2388[57] A/V core integrated IR controllers

This patch is primarily a port of the integrated IR controller code in
cx23885/cx23888-ir.c.  Right now, only the CX2388[57] AV core will
really try to set up IR. This IR support, by design, still requires the
bridge driver to do final IO pin mux configuration and setup of the IR
controller parameters.

For the CX2388[578] chips, enabling the AV Core for IR also starts
sending Audio and Video interrupts to the bridge driver.  For
CX2388[578] chips audio and video interrupts are ignored and
acknowledged when they happen.

IR interrupt handling and status logging is exluded for the CX23888
which does not have an IR controller on the AV core.

Note that experimentation reveals that the IR irq enables on the
CX23885 have an inverted logic sense.  The CX23887 likely suffers from
the same quirk.  For these chips, those irq enable bits are handled
as interrupt disables.

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