watchdog: bcm47xx_wdt.c: allow enabling on BCM5301X arch

BCM5301X (ARCH_BCM_5301X) is a new Broadcom architecture using the same
SoC bus driver (bcma) as BCM47XX but based on ARM instead of MIPS.
Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

drivers/watchdog/Kconfig

@@ -1113,7 +1113,7 @@ config ATH79_WDT
 
 config BCM47XX_WDT
 	tristate "Broadcom BCM47xx Watchdog Timer"
-	depends on BCM47XX
+	depends on BCM47XX || ARCH_BCM_5301X
 	select WATCHDOG_CORE
 	help
 	  Hardware driver for the Broadcom BCM47xx Watchdog Timer.