microblaze/of: Use generic rule to build dtb's

Modify arch/powerpc/boot/Makefile to use dtc command in
scripts/Makefile.lib

Signed-off-by: Dirk Brandewie <[e-mail]>
Signed-off-by: Grant Likely <[e-mail]>

arch/microblaze/boot/Makefile

···
 
 OBJCOPYFLAGS := -O binary
 
-# Where the DTS files live
-dtstree         := $(srctree)/$(src)/dts
-
 # Ensure system.dtb exists
 $(obj)/linked_dtb.o: $(obj)/system.dtb
 
···
 	$(call if_changed,strip)
 	@echo 'Kernel: $@ is ready' ' (#'`cat .version`')'
 
-# Rule to build device tree blobs
-DTC = $(objtree)/scripts/dtc/dtc
 
 # Rule to build device tree blobs
-quiet_cmd_dtc = DTC     $@
-	cmd_dtc = $(DTC) -O dtb -o $(obj)/$*.dtb -b 0 -p 1024 $(dtstree)/$*.dts
+DTC_FLAGS := -p 1024
 
-$(obj)/%.dtb: $(dtstree)/%.dts FORCE
-	$(call if_changed,dtc)
+$(obj)/%.dtb: $(src)/dts/%.dts FORCE
+	$(call cmd,dtc)
 
 clean-files += *.dtb simpleImage.*.unstrip linux.bin.ub