dt-bindings: Fix generated example files getting added to schemas

Commit 837158b8 ("dt-bindings: Check the examples against the
schemas") started generating YAML encoded DT files to validate the
examples against the schema. When running 'make dt_binding_check' in
tree after the 1st time, the generated example .dt.yaml files are
mistakenly added to the list of schema files. Exclude *.example.dt.yaml
files from the search for schema files.

Fixes: 837158b8 ("dt-bindings: Check the examples against the schemas")
Reported-by: Guido Günther <agx@sigxcpu.org>
Tested-by: Guido Günther <agx@sigxcpu.org>
Signed-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/Makefile

@@ -19,7 +19,9 @@ quiet_cmd_mk_schema = SCHEMA  $@
 
 DT_DOCS = $(shell \
 	cd $(srctree)/$(src) && \
-	find * \( -name '*.yaml' ! -name $(DT_TMP_SCHEMA) \) \
+	find * \( -name '*.yaml' ! \
+		-name $(DT_TMP_SCHEMA) ! \
+		-name '*.example.dt.yaml' \) \
 	)
 
 DT_SCHEMA_FILES ?= $(addprefix $(src)/,$(DT_DOCS))