[IRDA]: IrCOMM discovery indication simplification

From: Ryan Reading <ryanr23@gmail.com>

Every IrCOMM socket is registered with the discovery subsystem, so we don't
need to loop over all of them for every discovery event. We just need to
do it for the registered IrCOMM socket.

Signed-off-by: Samuel Ortiz <samuel@sortiz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>