drm/msm/dp: Remove dp_display_is_ds_bridge()

This function is simply drm_dp_is_branch() so use that instead of
open-coding it.

Cc: Vinod Polimera <quic_vpolimer@quicinc.com>
Cc: Kuogee Hsieh <quic_khsieh@quicinc.com>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Tested-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
Reviewed-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/554989/
Link: https://lore.kernel.org/r/20230829184735.2841739-8-swboyd@chromium.orgSigned-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

drivers/gpu/drm/msm/dp/dp_display.c

@@ -341,19 +341,12 @@ static const struct component_ops dp_display_comp_ops = {
 	.unbind = dp_display_unbind,
 };
 
-static bool dp_display_is_ds_bridge(struct dp_panel *panel)
-{
-	return (panel->dpcd[DP_DOWNSTREAMPORT_PRESENT] &
-		DP_DWN_STRM_PORT_PRESENT);
-}
-
 static bool dp_display_is_sink_count_zero(struct dp_display_private *dp)
 {
 	drm_dbg_dp(dp->drm_dev, "present=%#x sink_count=%d\n",
 			dp->panel->dpcd[DP_DOWNSTREAMPORT_PRESENT],
 		dp->link->sink_count);
-	return dp_display_is_ds_bridge(dp->panel) &&
-		(dp->link->sink_count == 0);
+	return drm_dp_is_branch(dp->panel->dpcd) && dp->link->sink_count == 0;
 }
 
 static void dp_display_send_hpd_event(struct msm_dp *dp_display)