gpio: sim: fix a typo

Just noticed this when applying Andy's patch. s/childred/children/

Fixes: cb8c474 ("gpio: sim: new testing module")
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

drivers/gpio/gpio-sim.c

@@ -547,7 +547,7 @@ struct gpio_sim_bank {
 	 *
 	 * So we need to store the pointer to the parent struct here. We can
 	 * dereference it anywhere we need with no checks and no locking as
-	 * it's guaranteed to survive the childred and protected by configfs
+	 * it's guaranteed to survive the children and protected by configfs
 	 * locks.
 	 *
 	 * Same for other structures.