drm/amd/display: FEC configuration for dpia links in MST mode

[Why]
To fix the check condition for fec enable for dpia links in MST mode.

[How]
dc_link_should_enable_fec() to be used to check whether fec should be
enabled in MST mode.

Cc: Wayne Lin <wayne.lin@amd.com>
Reviewed-by: Jimmy Kizito <Jimmy.Kizito@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Meenakshikumar Somasundaram <meenakshikumar.somasundaram@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/dcn31/dcn31_dio_link_encoder.c

@@ -476,7 +476,7 @@ void dcn31_link_encoder_enable_dp_mst_output(
 
 		if (link) {
 			dpia_control.dpia_id = link->ddc_hw_inst;
-			dpia_control.fec_rdy = link->fec_state == dc_link_fec_ready ? 1 : 0;
+			dpia_control.fec_rdy = dc_link_should_enable_fec(link);
 		} else {
 			DC_LOG_ERROR("%s: Failed to execute DPIA enable DMUB command.\n", __func__);
 			BREAK_TO_DEBUGGER();