[ATALK]: Include asm/byteorder.h in linux/atalk.h

We're using __be16 in userland visible types, so we
have to include asm/byteorder.h so that works.
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/atalk.h

 #ifndef __LINUX_ATALK_H__
 #define __LINUX_ATALK_H__
 
+#include <asm/byteorder.h>
+
 /*
  * AppleTalk networking structures
  *