dt-bindings: watchdog: update bindings for MT7629 SoC

This updates dt-binding documentation for MT7629 SoC
Signed-off-by: Ryder Lee <ryder.lee@mediatek.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Matthias Brugger <matthias.bgg@gmail.com>
Signed-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

@@ -8,6 +8,7 @@ Required properties:
 	"mediatek,mt6797-wdt", "mediatek,mt6589-wdt": for MT6797
 	"mediatek,mt7622-wdt", "mediatek,mt6589-wdt": for MT7622
 	"mediatek,mt7623-wdt", "mediatek,mt6589-wdt": for MT7623
+	"mediatek,mt7629-wdt", "mediatek,mt6589-wdt": for MT7629
 
 - reg : Specifies base physical address and size of the registers.