rockchip: gpio: rk_gpio: use ROCKCHIP_GPIOS_PER_BANK as divider

The current divider to calculate the bank ID can change.
Given the Rockchip TRM not all gpio-banks have 32 pins per bank.
The "gpio-ranges" syntax allows multiple items with variable number
of pins. Use a constant ROCKCHIP_GPIOS_PER_BANK as fixed divider.

Signed-off-by: Johan Jonker <jbx6244@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
diff --git a/drivers/gpio/rk_gpio.c b/drivers/gpio/rk_gpio.c
index f7ad4d6..0a2acf1 100644
--- a/drivers/gpio/rk_gpio.c
+++ b/drivers/gpio/rk_gpio.c
@@ -160,7 +160,7 @@
 					     0, &args);
 	if (!ret || ret != -ENOENT) {
 		uc_priv->gpio_count = args.args[2];
-		priv->bank = args.args[1] / args.args[2];
+		priv->bank = args.args[1] / ROCKCHIP_GPIOS_PER_BANK;
 	} else {
 		uc_priv->gpio_count = ROCKCHIP_GPIOS_PER_BANK;
 		end = strrchr(dev->name, '@');