[source] include: Include new location for DT bindings

[LEDE Commits]

florian pushed a commit to source.git, branch master:
https://git.lede-project.org/818f36aa140d930e5de957eeb81f32f4d96a4bbb

commit 818f36aa140d930e5de957eeb81f32f4d96a4bbb
Author: Florian Fainelli <f.fainelli at gmail.com>
AuthorDate: Mon Oct 9 20:33:34 2017 -0700

    include: Include new location for DT bindings
    
    Starting with commit d5d332d3f7e8 ("devicetree: Move include prefixes
    from arch to separate directory") included in 4.12 and newer relocated
    the dt-bindings directory, so account for that while passing CPPFLAGS
    before DTC runs.
    
    Signed-off-by: Florian Fainelli <f.fainelli at gmail.com>
---
 include/image.mk | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/image.mk b/include/image.mk
index 3f5b454..fc6bf06 100644
--- a/include/image.mk
+++ b/include/image.mk
@@ -161,6 +161,7 @@ define Image/BuildDTB
 	$(TARGET_CROSS)cpp -nostdinc -x assembler-with-cpp \
 		-I$(DTS_DIR) \
 		-I$(DTS_DIR)/include \
+		-I$(LINUX_DIR)/include/ \
 		-undef -D__DTS__ $(3) \
 		-o $(2).tmp $(1)
 	$(LINUX_DIR)/scripts/dtc/dtc -O dtb \