tools: Include U-Boot libfdt headers from their actual path

There are no headers for libfdt in lib/libfdt, as they are instead
located in scripts/dtc/libfdt. Specifying lib/libfdt for headers
inclusion in host tools results in using the system libfdt headers,
which is not what we want. Change this to the proper path.
Signed-off-by: NPaul Kocialkowski <contact@paulk.fr>

tools/Makefile

@@ -244,7 +244,7 @@ endif # !LOGO_BMP
 #
 HOST_EXTRACFLAGS += -include $(srctree)/include/compiler.h \
 		$(patsubst -I%,-idirafter%, $(filter -I%, $(UBOOTINCLUDE))) \
-		-I$(srctree)/lib/libfdt \
+		-I$(srctree)/scripts/dtc/libfdt \
 		-I$(srctree)/tools \
 		-DUSE_HOSTCC \
 		-D__KERNEL_STRICT_NAMES \