arm: bcmbca: replace ARCH_BCM68360 symbols in Kconfig with BCM6856

As CONFIG_ARCH_BCM68360 is replaced with CONFIG_BCM6856, 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/gpio/Kconfig b/drivers/gpio/Kconfig
index 851f14d..df45bce 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -110,7 +110,7 @@
 
 config BCM6345_GPIO
 	bool "BCM6345 GPIO driver"
-	depends on DM_GPIO && (ARCH_BMIPS || ARCH_BCM68360 || \
+	depends on DM_GPIO && (ARCH_BMIPS || BCM6856 || \
 			       ARCH_BCM6858 || BCM63158 || \
 			       ARCH_BCM6753)
 	help