arm: bcmbca: replace ARCH_BCM6753 symbols in Kconfig with BCM6855

As CONFIG_ARCH_BCM6753 is replaced with CONFIG_BCM6855, update the
driver Kconfig to use the new config symbol.

Signed-off-by: William Zhang <william.zhang@broadcom.com>
Reviewed-by: Philippe Reynes <philippe.reynes@softathome.com>
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 3b726af..f1b1cf6 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -131,7 +131,7 @@
 config WDT_BCM6345
 	bool "BCM6345 watchdog timer support"
 	depends on WDT && (ARCH_BMIPS || BCM6856 || \
-			   BCM6858 || BCM63158 || ARCH_BCM6753)
+			   BCM6858 || BCM63158 || BCM6855)
 	help
 	  Select this to enable watchdog timer for BCM6345 SoCs.
 	  The watchdog timer is stopped when initialized.