drm/bridge/parade: Drop legacy GPIO header

This driver uses the new GPIO API from <linux/gpio/consumer.h>
so drop the inclusion of the legacy header.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20190708113154.12985-1-linus.walleij@linaro.org