drm/imx/dcss: stop using drm_bridge_connector_en/disable_hpd()

The functionality of drm_bridge_connector_enable_hpd() and
drm_bridge_connector_disable_hpd() is provided automatically by the
drm_kms_poll helpers. Stop calling these functions manually.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
[narmstrong: removed now unused kms var in dcss_dev_suspend|resume()]
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20221102180705.459294-5-dmitry.baryshkov@linaro.org