Add a "tidy" build option

It is sometimes desireable to clean up the byproducts of the build
process without removing the executable results. "make clean" is
close, but leaves the build directory with a large number of
*.depend* files. This new build option invokes make clean, and then
removes the depend files.

Signed-off-by: Andy Fleming <afleming@freescale.com>

Makefile

@@ -777,11 +777,14 @@ clean:
 		-o -name '*.o'	-o -name '*.a' -o -name '*.exe'	\) -print \
 		| xargs rm -f
 
-clobber:	clean
-	@find $(OBJTREE) -type f \( -name '*.depend*' \
-		-o -name '*.srec' -o -name '*.bin' -o -name u-boot.img \) \
-		-print0 \
-		| xargs -0 rm -f
+# Removes everything not needed for testing u-boot
+tidy:	clean
+	@find $(OBJTREE) -type f \( -name '*.depend*' \) -print | xargs rm -f
+
+clobber:	tidy
+	@find $(OBJTREE) -type f \( -name '*.srec' \
+		-o -name '*.bin' -o -name u-boot.img \) \
+		-print0 | xargs -0 rm -f
 	@rm -f $(OBJS) $(obj)*.bak $(obj)ctags $(obj)etags $(obj)TAGS \
 		$(obj)cscope.* $(obj)*.*~
 	@rm -f $(obj)u-boot $(obj)u-boot.map $(obj)u-boot.hex $(ALL-y)