spi: mediatek: Add bindings for mediatek MT8183 soc platform

This patch adds a DT binding documentation for the MT8183 soc.
Signed-off-by: NLeilk Liu <leilk.liu@mediatek.com>
Signed-off-by: NMark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/spi/spi-mt65xx.txt

@@ -8,6 +8,7 @@ Required properties:
     - mediatek,mt7622-spi: for mt7622 platforms
     - mediatek,mt8135-spi: for mt8135 platforms
     - mediatek,mt8173-spi: for mt8173 platforms
+    - mediatek,mt8183-spi: for mt8183 platforms
 
 - #address-cells: should be 1.