dt-bindings: Pass binding directory to validation tools

In order to have $ref's to schema files within the kernel, we need to
pass the base path of bindings to the schema validation tools.

Cc: Masahiro Yamada <[e-mail]>
Cc: Michal Marek <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Signed-off-by: Rob Herring <[e-mail]>

Documentation/devicetree/bindings/Makefile

···
 DT_MK_SCHEMA_FLAGS := $(if $(DT_SCHEMA_FILES), -u)
 
 quiet_cmd_chk_binding = CHKDT   $(patsubst $(srctree)/%,%,$<)
-      cmd_chk_binding = $(DT_DOC_CHECKER) $< ; \
+      cmd_chk_binding = $(DT_DOC_CHECKER) -u $(srctree)/$(src) $< ; \
                         $(DT_EXTRACT_EX) $< > $@
 
 $(obj)/%.example.dts: $(src)/%.yaml FORCE

scripts/Makefile.lib

···
 DT_TMP_SCHEMA := $(objtree)/$(DT_BINDING_DIR)/processed-schema.yaml
 
 quiet_cmd_dtb_check =	CHECK   $@
-      cmd_dtb_check =	$(DT_CHECKER) -p $(DT_TMP_SCHEMA) $@ ;
+      cmd_dtb_check =	$(DT_CHECKER) -u $(srctree)/$(DT_BINDING_DIR) -p $(DT_TMP_SCHEMA) $@ ;
 
 define rule_dtc_dt_yaml
 	$(call cmd_and_fixdep,dtc,yaml)