drm/amd/display: Return the exact value for debugging

[Why]
It's unnecessary to set operation_result as invalid reply when
p_notify->result != AUX_RET_SUCCESS.

[How]
Set operation_result as p_notify->result to better understand
the reason for the error

Reviewed-by: Ray Wu <[e-mail]>
Signed-off-by: Wayne Lin <[e-mail]>
Signed-off-by: Ray Wu <[e-mail]>
Tested-by: Daniel Wheeler <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

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

···
 					payload->address, payload->length,
 					p_notify->result);
 		}
-		*operation_result = AUX_RET_ERROR_INVALID_REPLY;
+		*operation_result = p_notify->result;
 		goto out;
 	}