Revert "kbuild: Enable DT schema checks for %.dtb targets"

This reverts commit 53182e81.

This added tool dependencies on various build systems using %.dtb
targets. Validation will need to be controlled by a kconfig or make
variable instead, but for now let's just revert it.
Signed-off-by: Rob Herring <robh@kernel.org>

Makefile

@@ -1374,17 +1374,17 @@ endif
 
 ifneq ($(dtstree),)
 
-%.dtb: dt_binding_check include/config/kernel.release scripts_dtc
-	$(Q)$(MAKE) $(build)=$(dtstree) $(dtstree)/$@ $(dtstree)/$*.dt.yaml
+%.dtb: include/config/kernel.release scripts_dtc
+	$(Q)$(MAKE) $(build)=$(dtstree) $(dtstree)/$@
 
-%.dtbo: dt_binding_check include/config/kernel.release scripts_dtc
-	$(Q)$(MAKE) $(build)=$(dtstree) $(dtstree)/$@ $(dtstree)/$*.dt.yaml
+%.dtbo: include/config/kernel.release scripts_dtc
+	$(Q)$(MAKE) $(build)=$(dtstree) $(dtstree)/$@
 
 PHONY += dtbs dtbs_install dtbs_check
 dtbs: include/config/kernel.release scripts_dtc
 	$(Q)$(MAKE) $(build)=$(dtstree)
 
-ifneq ($(filter dtbs_check %.dtb %.dtbo, $(MAKECMDGOALS)),)
+ifneq ($(filter dtbs_check, $(MAKECMDGOALS)),)
 export CHECK_DTBS=y
 dtbs: dt_binding_check
 endif