pinctrl: samsung: Add ifdef CONFIG_OF_GPIO guard for gc->of_node

This fixes below build error when !CONFIG_OF_GPIO.

CC drivers/pinctrl/pinctrl-samsung.o
drivers/pinctrl/pinctrl-samsung.c: In function 'samsung_pinctrl_parse_dt_pins':
drivers/pinctrl/pinctrl-samsung.c:557:19: warning: unused variable 'prop' [-Wunused-variable] drivers/pinctrl/pinctrl-samsung.c: In function 'samsung_gpiolib_register':
drivers/pinctrl/pinctrl-samsung.c:797:5: error: 'struct gpio_chip' has no member named 'of_node' make[2]: *** [drivers/pinctrl/pinctrl-samsung.o] Error 1
make[1]: *** [drivers/pinctrl] Error 2
make: *** [drivers] Error 2

This patch also removes unused variable 'prop' to silence the build warning.

---
 drivers/pinctrl/pinctrl-samsung.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

index fc34cac..8ea9735 100644
@@ -554,7 +554,6 @@ static int __devinit samsung_pinctrl_parse_dt_pins(struct platform_device *pdev,
 			unsigned int **pin_list, unsigned int *npins)
 {
 	struct device *dev = &pdev->dev;
-	struct property *prop;
 	struct pinctrl_pin_desc const *pdesc = pctl->pins;
 	unsigned int idx = 0, cnt;
 	const char *pin_name;

@@ -794,7 +793,9 @@ static int __devinit samsung_gpiolib_register(struct platform_device *pdev,
 		gc->base = ctrl->base + bank->pin_base;
 		gc->ngpio = bank->nr_pins;
 		gc->dev = &pdev->dev;
+#if defined(CONFIG_OF_GPIO)
 		gc->of_node = bank->of_node;
+#endif
 		gc->label = bank->name;
 
 		ret = gpiochip_add(gc);

1.7.9.5