sh: Fix SH-boards compile error

By Cleanup out-or-tree building for some boards (.depend)
(commit:c8a3b109f07f02342d097b30908965f7261d9f15)
because filse ware changed, some SH-boards have compile error.
I revised this problem.

Signed-off-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
diff --git a/cpu/sh3/Makefile b/cpu/sh3/Makefile
index a7eb1e2..587413d 100644
--- a/cpu/sh3/Makefile
+++ b/cpu/sh3/Makefile
@@ -32,7 +32,7 @@
 LIB	= $(obj)lib$(CPU).a
 
 SOBJS	= start.o
-OBJS	= cpu.o interrupts.o watchdog.o time.o cache.o
+COBJS	= cpu.o interrupts.o watchdog.o time.o cache.o
 
 SRCS	:= $(SOBJS:.o=.S) $(COBJS:.o=.c)
 OBJS	:= $(addprefix $(obj),$(COBJS))