drm/bridge: analogix_dp: Apply DP helper APIs to get adjusted voltages and pre-emphasises

drm/bridge: analogix_dp: Apply DP helper APIs to get adjusted voltages and pre-emphasises

Replace analogix_dp_get_adjust_request_voltage() and
analogix_dp_get_adjust_request_pre_emphasis() with existing DP helper
APIs with the same function.

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/20251110085823.1197472-5-damon.ding@rock-chips.com
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>