image.mk: force kernel rebuild on every run

DTS dependencies are not processed correctly so makes it safer against
poentially stale builds

Signed-off-by: Felix Fietkau <nbd@nbd.name>

include/image.mk

@@ -419,7 +419,7 @@ define Device/Build/initramfs
   $(BIN_DIR)/$$(KERNEL_INITRAMFS_IMAGE): $(KDIR)/tmp/$$(KERNEL_INITRAMFS_IMAGE)
 	cp $$^ $$@
 
-  $(KDIR)/tmp/$$(KERNEL_INITRAMFS_IMAGE): $(KDIR)/$$(KERNEL_INITRAMFS_NAME) $(CURDIR)/Makefile $$(KERNEL_DEPENDS)
+  $(KDIR)/tmp/$$(KERNEL_INITRAMFS_IMAGE): $(KDIR)/$$(KERNEL_INITRAMFS_NAME) $(CURDIR)/Makefile $$(KERNEL_DEPENDS) image_prepare
 	@rm -f $$@
 	$$(call concat_cmd,$$(KERNEL_INITRAMFS))
 endef
@@ -443,7 +443,7 @@ define Device/Build/kernel
     ifdef CONFIG_IB
       install: $$(KDIR_KERNEL_IMAGE)
     endif
-    $$(KDIR_KERNEL_IMAGE): $(KDIR)/$$(KERNEL_NAME) $(CURDIR)/Makefile $$(KERNEL_DEPENDS)
+    $$(KDIR_KERNEL_IMAGE): $(KDIR)/$$(KERNEL_NAME) $(CURDIR)/Makefile $$(KERNEL_DEPENDS) image_prepare
 	@rm -f $$@
 	$$(call concat_cmd,$$(KERNEL))
 	$$(if $$(KERNEL_SIZE),$$(call Build/check-size,$$(KERNEL_SIZE)))