Makefile: remove a cleaning target "tidy"

Before this commit, "make tidy" did
"make clean" + delete "*.depend*" files.

But, we do not have "*.depend*" files any more,
which means "make tidy" is the same as "make clean".

This commit removes the redandant target "tidy".

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
diff --git a/Makefile b/Makefile
index 1611957..ac7dccd 100644
--- a/Makefile
+++ b/Makefile
@@ -472,7 +472,7 @@
 endif
 
 # Targets which don't build the source code
-NON_BUILD_TARGETS = backup clean clobber distclean mrproper tidy unconfig %_config
+NON_BUILD_TARGETS = backup clean clobber distclean mrproper unconfig %_config
 
 # Only do the generic board check when actually building, not configuring
 ifeq ($(filter $(NON_BUILD_TARGETS),$(MAKECMDGOALS)),)
@@ -1119,11 +1119,7 @@
 		-o -name '*.cfgtmp' \) -print \
 		| xargs rm -f
 
-# Removes everything not needed for testing u-boot
-tidy:	clean
-	@find $(OBJTREE) -type f \( -name '*.depend*' \) -print | xargs rm -f
-
-clobber:	tidy
+clobber: clean
 	@find $(OBJTREE) -type f \( -name '*.srec' \
 		-o -name '*.bin' -o -name u-boot.img \) \
 		-print0 | xargs -0 rm -f