[ATALK]: linux/atalk.h needs net/sock.h

Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/atalk.h

 #ifndef __LINUX_ATALK_H__
 #define __LINUX_ATALK_H__
+
+#include <net/sock.h>
+
 /*
  * AppleTalk networking structures
  *