drm/bridge/nxp-ptn3460: Drop legacy GPIO headers

This driver uses exclusively the new GPIO API from
<linux/gpio/consumer.h> so just drop the old API headers.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190708113009.12723-1-linus.walleij@linaro.org


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>