include/image.mk: add a path variable for the dts folder

Signed-off-by: John Crispin <[email protected]>

SVN-Revision: 41789

include/image.mk

@@ -14,6 +14,7 @@ include $(INCLUDE_DIR)/host.mk
 override MAKEFLAGS=
 override MAKE:=$(SUBMAKE)
 KDIR=$(KERNEL_BUILD_DIR)
+DTS_DIR:=$(LINUX_DIR)/arch/$(ARCH)/boot/dts/
 
 IMG_PREFIX:=openwrt-$(BOARD)$(if $(SUBTARGET),-$(SUBTARGET))