Clean ups and preparation for IPC abstraction in the SOF driver

Merge series from Ranjani Sridharan <ranjani.sridharan@linux.intel.com>:

In preparation for adding support for the new IPC version that has been
introduced in the SOF firmware, this patch set includes some clean ups
and necessary modifications to commonly used functions that will be
re-used across different IPC-specific code.

diff --cc sound/soc/sof/intel/hda.c
Simple merge