media: lirc: report ir receiver overflow

If the driver reports that the hardware had an overflow, report this to
userspace. It would be nice to know when this happens, and not just get
a long space.

This change has been tested with lircd, ir-ctl, and ir-keytable.

Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>