ASoC: dt-bindings: audio-graph-port: add missing mclk-fs

audio-graph-port is missing "mclk-fs" on ports/port,
it is used not only endpoint. It is already defined on simple-card.
This patch fixup it.
Without this patch, we will get below warning.

${LINUX}/arch/arm64/boot/dts/renesas/r8a77951-ulcb-kf.dtb: audio-codec@44: ports: 'mclk-fs' does not match any of the regexes: '^port@[0-9a-f]+$', 'pinctrl-[0-9]+'
	From schema: ${LINUX}/Documentation/devicetree/bindings/sound/ti,pcm3168a.yaml
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://lore.kernel.org/r/87o7qp7rgp.wl-kuninori.morimoto.gx@renesas.comSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/sound/audio-graph-port.yaml

@@ -24,16 +24,14 @@ definitions:
         $ref: "/schemas/sound/dai-params.yaml#/$defs/dai-channels"
       convert-sample-format:
         $ref: "/schemas/sound/dai-params.yaml#/$defs/dai-sample-format"
+      mclk-fs:
+        $ref: "simple-card.yaml#/definitions/mclk-fs"
 
   endpoint-base:
     $ref: /schemas/graph.yaml#/$defs/endpoint-base
     properties:
       mclk-fs:
-        description: |
-          Multiplication factor between stream rate and codec mclk.
-          When defined, mclk-fs property defined in dai-link sub nodes are
-          ignored.
-        $ref: /schemas/types.yaml#/definitions/uint32
+        $ref: "simple-card.yaml#/definitions/mclk-fs"
       frame-inversion:
         description: dai-link uses frame clock inversion
         $ref: /schemas/types.yaml#/definitions/flag