staging: irda: remove remaining remants of irda code removal

There were some documentation locations that irda was mentioned, as well
as an old MAINTAINERS entry and the networking sysctl entries.  Clean
these all out as this stuff really is finally gone.

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/networking/ip-sysctl.txt

@@ -2126,18 +2126,3 @@ max_dgram_qlen - INTEGER
 
 	Default: 10
 
-
-UNDOCUMENTED:
-
-/proc/sys/net/irda/*
-	fast_poll_increase FIXME
-	warn_noreply_time FIXME
-	discovery_slots FIXME
-	slot_timeout FIXME
-	max_baud_rate FIXME
-	discovery_timeout FIXME
-	lap_keepalive_time FIXME
-	max_noreply_time FIXME
-	max_tx_data_size FIXME
-	max_tx_window FIXME
-	min_tx_turn_time FIXME