[XFS] lock validator: lockdep: small xfs init_rwsem() cleanup

init_rwsem() has no return value.  This is not a problem if init_rwsem()
is a function, but it's a problem if it's a do { ...  } while (0) macro. 
(which lockdep introduces) 

SGI-PV: 904196
SGI-Modid: xfs-linux-melb:xfs-kern:26082a
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Nathan Scott <nathans@sgi.com>

fs/xfs/linux-2.6/mrlock.h

 /*
- * Copyright (c) 2000-2005 Silicon Graphics, Inc.
+ * Copyright (c) 2000-2006 Silicon Graphics, Inc.
  * All Rights Reserved.
  *
  * This program is free software; you can redistribute it and/or
@@ -28,7 +28,7 @@ typedef struct {
 } mrlock_t;
 
 #define mrinit(mrp, name)	\
-	( (mrp)->mr_writer = 0, init_rwsem(&(mrp)->mr_lock) )
+	do { (mrp)->mr_writer = 0; init_rwsem(&(mrp)->mr_lock); } while (0)
 #define mrlock_init(mrp, t,n,s)	mrinit(mrp, n)
 #define mrfree(mrp)		do { } while (0)
 #define mraccess(mrp)		mraccessf(mrp, 0)