If an invalid stream is passed to snd_sof_ipc_msg_data() it won't
fill the provided object with data. The caller has to be able to
recognise such cases to avoid handling invalid data. Make the
function return an error when failing.

Signed-off-by: Guennadi Liakhovetski <[email protected]>
Reviewed-by: Péter Ujfalusi <[email protected]>
Reviewed-by: Kai Vehmanen <[email protected]>
Reviewed-by: Ranjani Sridharan <[email protected]>