drm/amd/display: Missing HPO instance added

[Why & How]
Number of encoder is set to 4 but only 3 instances are created.
Reviewed-by: Charlene Liu <Charlene.Liu@amd.com>
Acked-by: Brian Chang <Brian.Chang@amd.com>
Signed-off-by: Leo Chen <sancchen@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/dcn314/dcn314_resource.c

@@ -454,6 +454,7 @@ static const struct dcn31_hpo_dp_stream_encoder_registers hpo_dp_stream_enc_regs
 	hpo_dp_stream_encoder_reg_list(0),
 	hpo_dp_stream_encoder_reg_list(1),
 	hpo_dp_stream_encoder_reg_list(2),
+	hpo_dp_stream_encoder_reg_list(3)
 };
 
 static const struct dcn31_hpo_dp_stream_encoder_shift hpo_dp_se_shift = {