kbuild: fix single *.ko build

The single *.ko build is broken since commit f65a486 ("kbuild:
change module.order to list *.o instead of *.ko").

Fixes: f65a486 ("kbuild: change module.order to list *.o instead of *.ko")
Reported-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Marc Kleine-Budde <mkl@pengutronix.de>

Makefile

@@ -1986,7 +1986,7 @@ $(single-no-ko): $(build-dir)
 # Remove MODORDER when done because it is not the real one.
 PHONY += single_modules
 single_modules: $(single-no-ko) modules_prepare
-	$(Q){ $(foreach m, $(single-ko), echo $(extmod_prefix)$m;) } > $(MODORDER)
+	$(Q){ $(foreach m, $(single-ko), echo $(extmod_prefix)$(m:%.ko=%.o);) } > $(MODORDER)
 	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost
 ifneq ($(KBUILD_MODPOST_NOFINAL),1)
 	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modfinal