scripts: allow dtc to be overridden by env

Use the system's dtc by default, but allow it to be overridden by
the environment e.g. during inline builds.

Signed-off-by: Park Ju Hyung <[email protected]>

Author: arter97

Diff for: scripts/Makefile.lib

@@ -268,6 +268,7 @@ cmd_gzip = (cat $(filter-out FORCE,$^) | gzip -n -f -9 > $@) || \
 
 # DTC
 # ---------------------------------------------------------------------------
+DTC ?= dtc
 
 # Disable noisy checks by default
 ifeq ($(KBUILD_ENABLE_EXTRA_GCC_CHECKS),)
@@ -311,7 +312,7 @@ $(obj)/%.dtb.S: $(obj)/%.dtb
 quiet_cmd_dtc = DTC     $@
 cmd_dtc = mkdir -p $(dir ${dtc-tmp}) ; \
 	$(CPP) $(dtc_cpp_flags) -x assembler-with-cpp -o $(dtc-tmp) $< ; \
-	dtc -O dtb -o $@ -b 0 \
+	$(DTC) -O dtb -o $@ -b 0 \
 		$(addprefix -i,$(dir $<) $(DTC_INCLUDE)) $(DTC_FLAGS) \
 		-d $(depfile).dtc.tmp $(dtc-tmp) ; \
 	cat $(depfile).pre.tmp $(depfile).dtc.tmp > $(depfile)