drm/bridge: analogix_dp: Apply DP helper API drm_dp_channel_eq_ok()

drm/bridge: analogix_dp: Apply DP helper API drm_dp_channel_eq_ok()

Use existing DP helper API instead of analogix_dp_channel_eq_ok()
with the same function.

In addtion, remove unused function analogix_dp_get_lane_status()

Signed-off-by: Damon Ding <damon.ding@rock-chips.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Link: https://patch.msgid.link/20251110085823.1197472-4-damon.ding@rock-chips.com
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>