examples: Use scripts/Makefile.build

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
diff --git a/Makefile b/Makefile
index 8c585b6..b10d3b1 100644
--- a/Makefile
+++ b/Makefile
@@ -558,12 +558,9 @@
 $(LIBS):	depend $(SUBDIR_TOOLS)
 		$(MAKE) $(build) $(dir $(subst $(obj),,$@))
 
-tools:	depend
+$(SUBDIRS):	depend
 		$(MAKE) $(build) $@ all
 
-$(filter-out tools,$(SUBDIRS)):	depend
-		$(MAKE) -C $@ all
-
 $(SUBDIR_EXAMPLES-y): $(obj)u-boot
 
 $(obj)u-boot.lds: $(LDSCRIPT) depend