dt-bindings: spi: add mt8192-nor compatible string

Add MT8192 spi-nor controller support.
Signed-off-by: Ikjoon Jang <ikjn@chromium.org>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20201006155010.v5.1.I4cd089ef1fe576535c6b6e4f1778eaab1c4441cf@changeidSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/spi/mediatek,spi-mtk-nor.yaml

@@ -30,6 +30,7 @@ properties:
               - mediatek,mt7622-nor
               - mediatek,mt7623-nor
               - mediatek,mt7629-nor
+              - mediatek,mt8192-nor
           - enum:
               - mediatek,mt8173-nor
       - items: