base-files: Allow subtargets to define base-files.mk

Signed-off-by: Florian Fainelli <[email protected]>

package/base-files/Makefile

@@ -171,6 +171,7 @@ endef
 
 ifneq ($(DUMP),1)
   -include $(PLATFORM_DIR)/base-files.mk
+  -include $(PLATFORM_SUBDIR)/base-files.mk
 endif
 
 $(eval $(call BuildPackage,base-files))