spi: update spi master bindings for MT8195 SoC

Add a DT binding documentation for the MT8195 soc.
Signed-off-by: leilk.liu <leilk.liu@mediatek.com>
Link: https://lore.kernel.org/r/20210322055244.30179-2-leilk.liu@mediatek.comSigned-off-by: Mark Brown <broonie@kernel.org>

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

@@ -12,6 +12,7 @@ Required properties:
     - mediatek,mt8173-spi: for mt8173 platforms
     - mediatek,mt8183-spi: for mt8183 platforms
     - "mediatek,mt8192-spi", "mediatek,mt6765-spi": for mt8192 platforms
+    - "mediatek,mt8195-spi", "mediatek,mt6765-spi": for mt8195 platforms
     - "mediatek,mt8516-spi", "mediatek,mt2712-spi": for mt8516 platforms
     - "mediatek,mt6779-spi", "mediatek,mt6765-spi": for mt6779 platforms