[PATCH] missing includes from infiniband merge

indirect chains of includes are arch-specific and can't
be relied upon...  (hell, even attempt to build it for
itanic would trigger vmalloc.h ones; err.h triggers
on e.g. alpha).

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/infiniband/core/mad_priv.h

@@ -38,6 +38,7 @@
 #define __IB_MAD_PRIV_H__
 
 #include <linux/completion.h>
+#include <linux/err.h>
 #include <linux/pci.h>
 #include <linux/workqueue.h>
 #include <rdma/ib_mad.h>