drm/msm/dsi: Drop unused GPIO includes

This DSI driver uses the new descriptor API so these old
GPIO API includes are surplus.

Cc: Rob Clark <robdclark@gmail.com>
Cc: Sean Paul <sean@poorly.run>
Cc: linux-arm-msm@vger.kernel.org
Cc: freedreno@lists.freedesktop.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>