drivers/gpio/da8xx_gpio.c: Fix build warning

Fix:
da8xx_gpio.c: In function 'gpio_toggle_value':
da8xx_gpio.c:208:23: warning: variable 'bank' set but not used
[-Wunused-but-set-variable]

Signed-off-by: Anatolij Gustschin <agust@denx.de>

drivers/gpio/da8xx_gpio.c

@@ -205,9 +205,6 @@ void gpio_free(int gp)
 
 void gpio_toggle_value(int gp)
 {
-	struct davinci_gpio *bank;
-
-	bank = GPIO_BANK(gp);
 	gpio_set_value(gp, !gpio_get_value(gp));
 }