kbuild: specify modules(_install) as PHONY rather than FORCE

As in other places, PHONY is a better fit for "modules" and
"modules_install".
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Michal Marek <mmarek@suse.com>

Makefile

@@ -1208,7 +1208,8 @@ else # CONFIG_MODULES
 # Modules not configured
 # ---------------------------------------------------------------------------
 
-modules modules_install: FORCE
+PHONY += modules modules_install
+modules modules_install:
 	@echo >&2
 	@echo >&2 "The present kernel configuration has modules disabled."
 	@echo >&2 "Type 'make config' and enable loadable module support."