V4L/DVB: IR: extend interfaces to support more device settings

LIRC: add new IOCTL that enables learning mode (wide band receiver)
Still missing features: carrier report & timeout reports.
Will need to pack these into ir_raw_event

Signed-off-by: Maxim Levitsky <maximlevitsky@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>