ASoC: SOF: Extend the IPC ops optionality

Merge series from Peter Ujfalusi <peter.ujfalusi@linux.intel.com>:

This series will extend the IPC ops optionality to cover it up to the existence
of the top level ipc pointer itself. There is no functionality change.

The reason for the extended optionality is that we have "DSPless"
debug/development support coming up (currently it is in SOF's topic/sof-dev
stable branch) initially supporting Intel's HDA platforms.

As the name suggests, in this mode the DSP is completely ignored by the linux
driver stack (no firmware loaded, only using HDA directly).

The DSPless mode is aimed to help us to verify our Linux stack on new platforms
where the firmware is not yet in the state that we can reliably use it, but the
hardware and programming flows can be tested already.
There is no plan to make DSPless a production target for SOF Linux stack.

While this is preparatory series aimed to unblock the DSPless support, it has
been integrated into sof-dev separately and we have lots of new features
depending on it (went in between this set and the DSPless support).

I still have some minor tasks to complete for the DSPless to make it a bit more
versatile, but I don't want to block other, stable features for upstreaming.