kbuild: always run gcc -E on *.dts, remove cmd_dtc_cpp

Replace cmd_dtc with cmd_dtc_cpp, and delete the latter.

Previously, a special file extension (.dtsp) was required to trigger
the C pre-processor to run on device tree files. This was ugly. Now that
previous changes have enhanced cmd_dtc_cpp to collect dependency
information from both gcc -E and dtc, we can transparently run the pre-
processor on all device tree files, irrespective of whether they
use /include/ or #include syntax to include *.dtsi.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Rob Herring <rob.herring@calxeda.com>

scripts/Makefile.lib

@@ -269,21 +269,17 @@ $(obj)/%.dtb.S: $(obj)/%.dtb
 	$(call cmd,dt_S_dtb)
 
 quiet_cmd_dtc = DTC     $@
-cmd_dtc = $(objtree)/scripts/dtc/dtc -O dtb -o $@ -b 0 $(DTC_FLAGS) -d $(depfile) $<
+cmd_dtc = $(CPP) $(dtc_cpp_flags) -x assembler-with-cpp -o $(dtc-tmp) $< ; \
+	$(objtree)/scripts/dtc/dtc -O dtb -o $@ -b 0 \
+		-i $(srctree)/arch/$(SRCARCH)/boot/dts $(DTC_FLAGS) \
+		-d $(depfile).dtc $(dtc-tmp) ; \
+	cat $(depfile).pre $(depfile).dtc > $(depfile)
 
 $(obj)/%.dtb: $(src)/%.dts FORCE
 	$(call if_changed_dep,dtc)
 
 dtc-tmp = $(subst $(comma),_,$(dot-target).dts)
 
-quiet_cmd_dtc_cpp = DTC+CPP $@
-cmd_dtc_cpp = $(CPP) $(dtc_cpp_flags) -x assembler-with-cpp -o $(dtc-tmp) $< ; \
-	$(objtree)/scripts/dtc/dtc -O dtb -o $@ -b 0 $(DTC_FLAGS) -d $(depfile).dtc $(dtc-tmp) ; \
-	cat $(depfile).pre $(depfile).dtc > $(depfile)
-
-$(obj)/%.dtb: $(src)/%.dtsp FORCE
-	$(call if_changed_dep,dtc_cpp)
-
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