unix_diag: Include unix_diag.h into header-y target

The headers check complains it should include the linux/types.h
withing, thus add this one.

Signed-off-by: Pavel Emelyanov <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/linux/Kbuild

···
 header-y += in_route.h
 header-y += sock_diag.h
 header-y += inet_diag.h
+header-y += unix_diag.h
 header-y += inotify.h
 header-y += input.h
 header-y += ioctl.h

include/linux/unix_diag.h

···
 #ifndef __UNIX_DIAG_H__
 #define __UNIX_DIAG_H__
 
+#include <linux/types.h>
+
 struct unix_diag_req {
 	__u8	sdiag_family;
 	__u8	sdiag_protocol;