staging: irda: update MAINTAINERS

Now that the IRDA code has moved under drivers/staging/irda/, update the
MAINTAINERS file with the new location.

Reported-by: Joe Perches <joe@perches.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>