mkbootimg: add exynos subdir to possible_dtb_dirs

Change-Id: I70e5e0817ff0b63da7df3ab63f42b815170096e4
diff --git a/mkbootimg.mk b/mkbootimg.mk
index ce320a0..d3db2e5 100644
--- a/mkbootimg.mk
+++ b/mkbootimg.mk
@@ -35,7 +35,7 @@
 possible_dtb_dirs = $(KERNEL_OUT)/arch/$(KERNEL_ARCH)/boot/
 else
 # Most specific paths must come first in possible_dtb_dirs
-possible_dtb_dirs = $(KERNEL_OUT)/arch/$(KERNEL_ARCH)/boot/dts/ $(KERNEL_OUT)/arch/$(KERNEL_ARCH)/boot/
+possible_dtb_dirs = $(KERNEL_OUT)/arch/$(KERNEL_ARCH)/boot/dts/exynos/ $(KERNEL_OUT)/arch/$(KERNEL_ARCH)/boot/dts/ $(KERNEL_OUT)/arch/$(KERNEL_ARCH)/boot/
 endif
 
 define build-dtimage-target