drm/amd/display: Support mappable encoders when transmitting training patterns.

[Why & How]
Add support for transmitting training pattern sequences for links whose
encoders have been dynamically assigned.

Signed-off-by: Jimmy Kizito <[e-mail]>
Reviewed-by: Jun Lei <[e-mail]>
Acked-by: Stylon Wang <[e-mail]>
Tested-by: Daniel Wheeler <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/amd/display/dc/core/dc_link_hwss.c

···
 	uint32_t custom_pattern_size)
 {
 	struct encoder_set_dp_phy_pattern_param pattern_param = {0};
-	struct link_encoder *encoder = link->link_enc;
+	struct link_encoder *encoder;
+
+	/* Access link encoder based on whether it is statically
+	 * or dynamically assigned to a link.
+	 */
+	if (link->is_dig_mapping_flexible &&
+			link->dc->res_pool->funcs->link_encs_assign)
+		encoder = link_enc_cfg_get_link_enc_used_by_link(link->dc->current_state, link);
+	else
+		encoder = link->link_enc;
 
 	pattern_param.dp_phy_pattern = test_pattern;
 	pattern_param.custom_pattern = custom_pattern;