kbuild: fix DT binding schema rule to detect command line changes

This if_change_rule is not working properly; it cannot detect any
command line change.

The reason is because cmd-check in scripts/Kbuild.include compares
$(cmd_$@) and $(cmd_$1), but cmd_dtc_dt_yaml does not exist here.

For if_change_rule to work properly, the stem part of cmd_* and rule_*
must match. Because this cmd_and_fixdep invokes cmd_dtc, this rule must
be named rule_dtc.

Fixes: 4f0e3a57 ("kbuild: Add support for DT binding schema checks")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Rob Herring <robh@kernel.org>

scripts/Makefile.lib

@@ -302,13 +302,13 @@ DT_TMP_SCHEMA := $(objtree)/$(DT_BINDING_DIR)/processed-schema.yaml
 quiet_cmd_dtb_check =	CHECK   $@
       cmd_dtb_check =	$(DT_CHECKER) -u $(srctree)/$(DT_BINDING_DIR) -p $(DT_TMP_SCHEMA) $@ ;
 
-define rule_dtc_dt_yaml
+define rule_dtc
 	$(call cmd_and_fixdep,dtc,yaml)
 	$(call cmd,dtb_check)
 endef
 
 $(obj)/%.dt.yaml: $(src)/%.dts $(DTC) $(DT_TMP_SCHEMA) FORCE
-	$(call if_changed_rule,dtc_dt_yaml)
+	$(call if_changed_rule,dtc)
 
 dtc-tmp = $(subst $(comma),_,$(dot-target).dts.tmp)