gpiolib: remove set but not used variable 'config'

drivers/gpio/gpiolib.c: In function gpio_set_config:
drivers/gpio/gpiolib.c:3053:16: warning:
 variable config set but not used [-Wunused-but-set-variable]

commit d90f3685 ("gpiolib: have a single place
of calling set_config()") left behind this unused variable.
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Link: https://lore.kernel.org/r/20200108121117.45060-1-yuehaibing@huawei.comReviewed-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpiolib.c

@@ -3043,7 +3043,6 @@ static int gpio_do_set_config(struct gpio_chip *gc, unsigned int offset,
 static int gpio_set_config(struct gpio_chip *gc, unsigned int offset,
 			   enum pin_config_param mode)
 {
-	unsigned long config;
 	unsigned arg;
 
 	switch (mode) {
@@ -3057,7 +3056,6 @@ static int gpio_set_config(struct gpio_chip *gc, unsigned int offset,
 		arg = 0;
 	}
 
-	config = PIN_CONF_PACKED(mode, arg);
 	return gpio_do_set_config(gc, offset, mode);
 }