pinctrl: core: Remove duplicated word from devm_pinctrl_unregister()

Remove duplicated "which" from devm_pinctrl_unregister() kernel doc
description.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Link: https://lore.kernel.org/r/8b75e5dfd9363f35ebdd7812e119757379678f97.1629877281.git.michal.simek@xilinx.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/core.c

@@ -2306,7 +2306,7 @@ EXPORT_SYMBOL_GPL(devm_pinctrl_register_and_init);
 
 /**
  * devm_pinctrl_unregister() - Resource managed version of pinctrl_unregister().
- * @dev: device for which which resource was allocated
+ * @dev: device for which resource was allocated
  * @pctldev: the pinctrl device to unregister.
  */
 void devm_pinctrl_unregister(struct device *dev, struct pinctrl_dev *pctldev)