dt-bindings: watchdog: Add compatible for Mediatek MT7986

This commit adds dt-binding documentation of watchdog for Mediatek MT7986
SoC Platform.
Signed-off-by: Sam Shih <sam.shih@mediatek.com>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20210726071439.14248-11-sam.shih@mediatek.comSigned-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

Documentation/devicetree/bindings/watchdog/mtk-wdt.txt

@@ -13,6 +13,7 @@ Required properties:
 	"mediatek,mt7622-wdt", "mediatek,mt6589-wdt": for MT7622
 	"mediatek,mt7623-wdt", "mediatek,mt6589-wdt": for MT7623
 	"mediatek,mt7629-wdt", "mediatek,mt6589-wdt": for MT7629
+	"mediatek,mt7986-wdt", "mediatek,mt6589-wdt": for MT7986
 	"mediatek,mt8183-wdt": for MT8183
 	"mediatek,mt8516-wdt", "mediatek,mt6589-wdt": for MT8516
 	"mediatek,mt8192-wdt": for MT8192