[source] build: fix regression in append-dtb fix

[LEDE Commits]

nbd pushed a commit to source.git, branch master:
https://git.lede-project.org/fae5f02912cf358eee9e99e4f54f047f1788ca16

commit fae5f02912cf358eee9e99e4f54f047f1788ca16
Author: Felix Fietkau <nbd at nbd.name>
AuthorDate: Fri Nov 3 10:46:24 2017 +0100

    build: fix regression in append-dtb fix
    
    Strip whitespace from DTS directory
    Put the dependency earlier in the chain to avoid make errors
    
    Signed-off-by: Felix Fietkau <nbd at nbd.name>
---
 include/image.mk | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/include/image.mk b/include/image.mk
index 9ab139c..2d7b1ef 100644
--- a/include/image.mk
+++ b/include/image.mk
@@ -438,17 +438,16 @@ endef
 ifndef IB
 define Device/Build/dtb
   $(KDIR)/image-$(1).dtb: FORCE
-	$(call Image/BuildDTB,$(2)/$(1).dts,$$@)
+	$(call Image/BuildDTB,$(strip $(2))/$(1).dts,$$@)
 
-  $(3): $(KDIR)/image-$(1).dtb
+  image_prepare: $(KDIR)/image-$(1).dtb
 endef
 endif
 
 define Device/Build/kernel
   $$(eval $$(foreach dts,$$(DEVICE_DTS), \
 	$$(call Device/Build/dtb,$$(dts), \
-		$$(if $$(DEVICE_DTS_DIR),$$(DEVICE_DTS_DIR),$$(DTS_DIR)),\
-		$$(KDIR_KERNEL_IMAGE) $(KDIR)/$$(KERNEL_INITRAMFS_NAME) \
+		$$(if $$(DEVICE_DTS_DIR),$$(DEVICE_DTS_DIR),$$(DTS_DIR)) \
 	) \
   ))