gpio: mmio: remove untrue leftover comment

The comment should have been removed when new GPIO direction
definitions were taken in use as the function logic was changed. It
is now perfectly valid and Ok to hit the return from the bottom of
the direction getting function.
Signed-off-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>

drivers/gpio/gpio-mmio.c

@@ -386,7 +386,6 @@ static int bgpio_get_dir(struct gpio_chip *gc, unsigned int gpio)
 		if (!(gc->read_reg(gc->reg_dir_in) & bgpio_line2mask(gc, gpio)))
 			return GPIO_LINE_DIRECTION_OUT;
 
-	/* This should not happen */
 	return GPIO_LINE_DIRECTION_IN;
 }