kbuild: arch{mrproper,clean} no longer mandatory

archmrproper and archclean is declared .PHONY in top-level Makefile,
therefore they are no longer mandatory in arch/$(ARCH)/Makefile.

Makefile

@@ -705,14 +705,14 @@ MRPROPER_DIRS += \
 
 # clean - Delete all intermediate files
 #
-clean-dirs += $(ALL_SUBDIRS) Documentation/DocBook scripts
-
-$(addprefix _clean_,$(clean-dirs)):
+clean-dirs += $(addprefix, _clean_,$(ALL_SUBDIRS) Documentation/DocBook scripts)
+.PHONY: $(clean-dirs) clean archclean mrproper archmrproper distclean
+$(clean-dirs):
 	$(Q)$(MAKE) $(clean)=$(patsubst _clean_%,%,$@)
 
 quiet_cmd_rmclean = RM  $$(CLEAN_FILES)
 cmd_rmclean	  = rm -f $(CLEAN_FILES)
-clean: archclean $(addprefix _clean_,$(clean-dirs))
+clean: archclean $(clean-dirs)
 	$(call cmd,rmclean)
 	@find . $(RCS_FIND_IGNORE) \
 	 	\( -name '*.[oas]' -o -name '*.ko' -o -name '.*.cmd' \

arch/i386/Makefile

@@ -3,8 +3,7 @@
 #
 # This file is included by the global makefile so that you can add your own
 # architecture-specific flags and dependencies. Remember to do have actions
-# for "archclean" and "archdep" for cleaning up and making dependencies for
-# this architecture
+# for "archclean" cleaning up for this architecture.
 #
 # This file is subject to the terms and conditions of the GNU General Public
 # License.  See the file "COPYING" in the main directory of this archive
@@ -92,8 +91,7 @@ AFLAGS += $(mflags-y)
 
 boot := arch/i386/boot
 
-.PHONY: zImage bzImage compressed zlilo bzlilo zdisk bzdisk install \
-		clean archclean archmrproper
+.PHONY: zImage bzImage compressed zlilo bzlilo zdisk bzdisk install
 
 all: bzImage