pinctrl: core: Add missing #ifdef CONFIG_GPIOLIB

To fix the following build warnings when CONFIG_GPIOLIB=n.

drivers/pinctrl/core.c:1607:20: warning: unused variable 'chip' [-Wunused-variable]
 1608 |  struct gpio_chip *chip;
      |                    ^~~~
drivers/pinctrl/core.c:1606:15: warning: unused variable 'gpio_num' [-Wunused-variable]
 1607 |  unsigned int gpio_num;
      |               ^~~~~~~~
drivers/pinctrl/core.c:1605:29: warning: unused variable 'range' [-Wunused-variable]
 1606 |  struct pinctrl_gpio_range *range;
      |                             ^~~~~

Fixes: f1b206cf ("pinctrl: core: print gpio in pins debugfs file")
Signed-off-by: He Zhe <zhe.he@windriver.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20201028103921.22486-1-zhe.he@windriver.comSigned-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/core.c

@@ -1602,9 +1602,11 @@ static int pinctrl_pins_show(struct seq_file *s, void *what)
 	struct pinctrl_dev *pctldev = s->private;
 	const struct pinctrl_ops *ops = pctldev->desc->pctlops;
 	unsigned i, pin;
+#ifdef CONFIG_GPIOLIB
 	struct pinctrl_gpio_range *range;
 	unsigned int gpio_num;
 	struct gpio_chip *chip;
+#endif
 
 	seq_printf(s, "registered pins: %d\n", pctldev->desc->npins);