gpio: sim: fix uninitialized ret variable

Building with clang returns this error:

gpio-sim.c:889:7: error: variable 'ret' is uninitialized
  when used here

ret should be the status of the call to
gpio_sim_make_bank_swnode stored in bank->swnode.

Fixes: 83960fcf4818 ("gpio: sim: new testing module")
Signed-off-by: Tom Rix <trix@redhat.com>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>

drivers/gpio/gpio-sim.c

@@ -886,7 +886,8 @@ static int gpio_sim_device_activate_unlocked(struct gpio_sim_device *dev)
 
 	list_for_each_entry(bank, &dev->bank_list, siblings) {
 		bank->swnode = gpio_sim_make_bank_swnode(bank, swnode);
-		if (ret) {
+		if (IS_ERR(bank->swnode)) {
+			ret = PTR_ERR(bank->swnode);
 			gpio_sim_remove_swnode_recursive(swnode);
 			return ret;
 		}