V4L/DVB: ir-core: move decoding state to ir_raw_event_ctrl

This patch moves the state from each raw decoder into the
ir_raw_event_ctrl struct.

This allows the removal of code like this:

        spin_lock(&decoder_lock);
        list_for_each_entry(data, &decoder_list, list) {
                if (data->ir_dev == ir_dev)
                        break;
        }
        spin_unlock(&decoder_lock);
        return data;

which is currently run for each decoder on each event in order
to get the client-specific decoding state data.

In addition, ir decoding modules and ir driver module load
order is now independent. Centralizing the data also allows
for a nice code reduction of about 30% per raw decoder as
client lists and client registration callbacks are no longer
necessary (but still kept around for the benefit of the lirc
decoder).

Out-of-tree modules can still use a similar trick to what
the raw decoders did before this patch until they are merged.

Signed-off-by: David Härdeman <david@hardeman.nu>
Acked-by: Jarod Wilson <jarod@redhat.com>
Tested-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>