irda: Remove BKL instances from irnet

The code intends to lock the irnet_socket, so adding a mutex to it allows
for a complet BKL removal.

Signed-off-by: Samuel Ortiz <samuel@sortiz.org>
diff --git a/net/irda/irnet/irnet.h b/net/irda/irnet/irnet.h
index 4300df3..0d82ff5 100644
--- a/net/irda/irnet/irnet.h
+++ b/net/irda/irnet/irnet.h
@@ -458,6 +458,8 @@
   int			disco_index;	/* Last read in the discovery log */
   int			disco_number;	/* Size of the discovery log */
 
+  struct mutex		lock;
+
 } irnet_socket;
 
 /*