kbuild: set KBUILD_MODULES=1 all the time for single target %/

It is fine to set KBUILD_MODULES=1 when CONFIG_MODULES is disabled.
It is actually how "make allnoconfig all" works.

On the other hand, KBUILD_MODULES=1 is unneeded for the %.ko pattern.
It is just a matter of whether modules.order is generated or not.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

Makefile

@@ -1716,16 +1716,13 @@ endif
 
 # Modules
 /: prepare FORCE
-	$(Q)$(MAKE) KBUILD_MODULES=$(if $(CONFIG_MODULES),1) \
-	$(build)=$(build-dir)
+	$(Q)$(MAKE) KBUILD_MODULES=1 $(build)=$(build-dir)
 # Make sure the latest headers are built for Documentation
 Documentation/ samples/: headers_install
 %/: prepare FORCE
-	$(Q)$(MAKE) KBUILD_MODULES=$(if $(CONFIG_MODULES),1) \
-	$(build)=$(build-dir)
+	$(Q)$(MAKE) KBUILD_MODULES=1 $(build)=$(build-dir)
 %.ko: prepare FORCE
-	$(Q)$(MAKE) KBUILD_MODULES=$(if $(CONFIG_MODULES),1)   \
-	$(build)=$(build-dir) $(@:.ko=.o)
+	$(Q)$(MAKE) $(build)=$(build-dir) $(@:.ko=.o)
 	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost
 
 # FIXME Should go into a make.lib or something