sh: Add support zimageboot command for Renesas SH

Curent U-Boot can boot zImage by use the "go" command.
But this is not right method. And this method can not set command-line
to linux kernel.
zimageboot sets command-line in environment of u-boot in linux kernel,
and provides function to boot it.

Signed-off-by: Nobuhiro Iwamatsu <nobuhiro.iwamatsu.yj@renesas.com>
diff --git a/arch/sh/lib/Makefile b/arch/sh/lib/Makefile
index 7f60396..c0670cb 100644
--- a/arch/sh/lib/Makefile
+++ b/arch/sh/lib/Makefile
@@ -31,6 +31,9 @@
 else
 COBJS-y	+= time.o
 endif
+ifeq ($(CONFIG_CMD_SH_ZIMAGEBOOT),y)
+COBJS-y += zimageboot.o
+endif
 
 SRCS	:= $(SOBJS-y:.o=.S) $(COBJS-y:.o=.c)
 OBJS	:= $(addprefix $(obj),$(SOBJS-y) $(COBJS-y))