pinctrl: sp7021: fix unused function warning

sppctl_gpio_inv_get is only used from the debugfs code inside
of an #ifdef, so we get a warning without that:

drivers/pinctrl/sunplus/sppctl.c:393:12: error: 'sppctl_gpio_inv_get' defined but not used [-Werror=unused-function]
  393 | static int sppctl_gpio_inv_get(struct gpio_chip *chip, unsigned int offset)
      |            ^~~~~~~~~~~~~~~~~~~

Replace the #ifdef with an IS_ENABLED() check that avoids the warning.

Fixes: aa74c44b ("pinctrl: Add driver for Sunplus SP7021")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20221215163822.542622-1-arnd@kernel.orgSigned-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/sunplus/sppctl.c

@@ -499,7 +499,6 @@ static int sppctl_gpio_set_config(struct gpio_chip *chip, unsigned int offset,
 	return 0;
 }
 
-#ifdef CONFIG_DEBUG_FS
 static void sppctl_gpio_dbg_show(struct seq_file *s, struct gpio_chip *chip)
 {
 	const char *label;
@@ -521,7 +520,6 @@ static void sppctl_gpio_dbg_show(struct seq_file *s, struct gpio_chip *chip)
 		seq_puts(s, "\n");
 	}
 }
-#endif
 
 static int sppctl_gpio_new(struct platform_device *pdev, struct sppctl_pdata *pctl)
 {
@@ -550,9 +548,8 @@ static int sppctl_gpio_new(struct platform_device *pdev, struct sppctl_pdata *pc
 	gchip->get              = sppctl_gpio_get;
 	gchip->set              = sppctl_gpio_set;
 	gchip->set_config       = sppctl_gpio_set_config;
-#ifdef CONFIG_DEBUG_FS
-	gchip->dbg_show         = sppctl_gpio_dbg_show;
-#endif
+	gchip->dbg_show         = IS_ENABLED(CONFIG_DEBUG_FS) ?
+				  sppctl_gpio_dbg_show : NULL;
 	gchip->base             = -1;
 	gchip->ngpio            = sppctl_gpio_list_sz;
 	gchip->names            = sppctl_gpio_list_s;