drm/amd/display: Retry AUX write when fail occurs

[Why]
In dm_dp_aux_transfer() now, we forget to handle AUX_WR fail cases. We
suppose every write wil get done successfully and hence some AUX
commands might not sent out indeed.

[How]
Check if AUX_WR success. If not, retry it.

Signed-off-by: Wayne Lin <[e-mail]>
Reviewed-by: Hersen Wu <[e-mail]>
Acked-by: Rodrigo Siqueira <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c

···
 	result = dc_link_aux_transfer_raw(TO_DM_AUX(aux)->ddc_service, &payload,
 				      &operation_result);
 
-	if (payload.write)
+	if (payload.write && result >= 0)
 		result = msg->size;
 
 	if (result < 0)