dt-bindings: serial: Add compatible for Mediatek MT8195

This commit adds dt-binding documentation of uart for Mediatek MT8195 SoC
Platform.
Signed-off-by: Seiya Wang <seiya.wang@mediatek.com>
Link: https://lore.kernel.org/r/20210319023427.16711-4-seiya.wang@mediatek.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/serial/mtk-uart.txt

@@ -20,6 +20,7 @@ Required properties:
   * "mediatek,mt8173-uart" for MT8173 compatible UARTS
   * "mediatek,mt8183-uart", "mediatek,mt6577-uart" for MT8183 compatible UARTS
   * "mediatek,mt8192-uart", "mediatek,mt6577-uart" for MT8192 compatible UARTS
+  * "mediatek,mt8195-uart", "mediatek,mt6577-uart" for MT8195 compatible UARTS
   * "mediatek,mt8516-uart" for MT8516 compatible UARTS
   * "mediatek,mt6577-uart" for MT6577 and all of the above