Instead of hardcoding the protocols into ir-core, add a register interface
for the IR protocol decoders, and convert ir-nec-decoder into a client of
ir-core.

With this approach, it is possible to dynamically load the needed IR protocols,
and to add a RAW IR interface module, registered as one IR raw protocol decoder.

This patch opens a way to register a lirc_dev interface to work as an userspace
IR protocol decoder.
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

Split the ir-common into two separate modules:
	- ir-core: it is the IR-independent functions;
	- ir-common: has the common part used by V4L drivers.
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

This is the first step of creating a common code for IR that can be
used by other input devices.

For now, keep IR dir at drivers/media, to easy the movement of the IR files,
but later patches may move it to drivers/IR or drivers/input/IR.

No functional changes is done on this patch.
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>