dt-bindings: watchdog: npcm: Add npcm845 compatible string

Add a compatible string for Nuvoton BMC NPCM845 watchdog.
Signed-off-by: Tomer Maimon <tmaimon77@gmail.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Documentation/devicetree/bindings/watchdog/nuvoton,npcm-wdt.txt

@@ -6,7 +6,8 @@ expiry.
 
 Required properties:
 - compatible      : "nuvoton,npcm750-wdt" for NPCM750 (Poleg), or
-                    "nuvoton,wpcm450-wdt" for WPCM450 (Hermon).
+                    "nuvoton,wpcm450-wdt" for WPCM450 (Hermon), or
+                    "nuvoton,npcm845-wdt" for NPCM845 (Arbel).
 - reg             : Offset and length of the register set for the device.
 - interrupts      : Contain the timer interrupt with flags for
                     falling edge.