drm/i915/mst: Always write CHICKEN_TRANS

Since we're asked to disable FECSTALL_DIS_DPTSTREAM_DPTTG when
the transcoder is disabled it seems prudent to also clear it
when enabliing the transcoder w/o FEC, just in case
someone else left it enabled by mistake.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231018154123.5479-5-ville.syrjala@linux.intel.comReviewed-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/display/intel_dp_mst.c

@@ -817,12 +817,14 @@ static void intel_mst_enable_dp(struct intel_atomic_state *state,
 	drm_dp_add_payload_part2(&intel_dp->mst_mgr, &state->base,
 				 drm_atomic_get_mst_payload_state(mst_state, connector->port));
 
-	if (DISPLAY_VER(dev_priv) >= 14 && pipe_config->fec_enable)
-		intel_de_rmw(dev_priv, MTL_CHICKEN_TRANS(trans), 0,
-			     FECSTALL_DIS_DPTSTREAM_DPTTG);
-	else if (DISPLAY_VER(dev_priv) >= 12 && pipe_config->fec_enable)
-		intel_de_rmw(dev_priv, CHICKEN_TRANS(trans), 0,
-			     FECSTALL_DIS_DPTSTREAM_DPTTG);
+	if (DISPLAY_VER(dev_priv) >= 14)
+		intel_de_rmw(dev_priv, MTL_CHICKEN_TRANS(trans),
+			     FECSTALL_DIS_DPTSTREAM_DPTTG,
+			     pipe_config->fec_enable ? FECSTALL_DIS_DPTSTREAM_DPTTG : 0);
+	else if (DISPLAY_VER(dev_priv) >= 12)
+		intel_de_rmw(dev_priv, CHICKEN_TRANS(trans),
+			     FECSTALL_DIS_DPTSTREAM_DPTTG,
+			     pipe_config->fec_enable ? FECSTALL_DIS_DPTSTREAM_DPTTG : 0);
 
 	intel_audio_sdp_split_update(pipe_config);