snd: iec958: split status creation and fill

In some situations, like a codec probe, we need to provide an IEC status
default but don't have access to the sampling rate and width yet since
no stream has been configured yet.

Each and every driver has its own default, whereas the core iec958 code
also has some buried in the snd_pcm_create_iec958_consumer functions.

Let's split these functions in two to provide a default that doesn't
rely on the sampling rate and width, and another function to fill them
when available.

Signed-off-by: Maxime Ripard <maxime@cerno.tech>