[PATCH] missing include in infiniband

use of IS_ERR/PTR_ERR in infiniband/core/agent.c, without a portable
chain of includes pulling err.h (breaks on a bunch of platforms).

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Roland Dreier <rolandd@cisco.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/infiniband/core/agent.h

@@ -39,6 +39,7 @@
 #ifndef __AGENT_H_
 #define __AGENT_H_
 
+#include <linux/err.h>
 #include <rdma/ib_mad.h>
 
 extern int ib_agent_port_open(struct ib_device *device, int port_num);