sh: plug vsyscall dir in to archclean.

The vsyscall targets are presently not cleaned up, so just handle it in
the archclean rule.

Reported-by: Magnus Damm <damm@igel.co.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
diff --git a/arch/sh/Makefile b/arch/sh/Makefile
index 0fe35cf..75d049b0 100644
--- a/arch/sh/Makefile
+++ b/arch/sh/Makefile
@@ -205,6 +205,7 @@
 
 archclean:
 	$(Q)$(MAKE) $(clean)=$(boot)
+	$(Q)$(MAKE) $(clean)=arch/sh/kernel/vsyscall
 
 define archhelp
 	@echo '* zImage 	           - Compressed kernel image'