image.mk: remove obsolete Build/mkfs overrides

Signed-off-by: Felix Fietkau <[email protected]>

include/image.mk

@@ -288,8 +288,6 @@ define BuildImage/mkfs
   .PHONY: mkfs-$(1)
   mkfs-$(1): kernel_prepare
 	$(Image/mkfs/$(1))
-	$(call Build/mkfs/default,$(1))
-	$(call Build/mkfs/$(1),$(1))
   $(KDIR)/root.$(1): mkfs-$(1)
 
 endef