drm/msm/hdmi: drop unused GPIO support

drm/msm/hdmi: drop unused GPIO support

The HDMI driver has code to configure extra GPIOs, which predates
pinctrl support. Nowadays all platforms should use pinctrl instead.
Neither of upstreamed Qualcomm platforms uses these properties, so it's
safe to drop them.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Patchwork: https://patchwork.freedesktop.org/patch/488858/
Link: https://lore.kernel.org/r/20220609122350.3157529-7-dmitry.baryshkov@linaro.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>