logging: Remove hda log backend

The HDA log backend has been buggy for some time, and the fixes are well
understood. The issue with HDA log as it is implemented today means
there are concurrency and ISR issues where it can deadlock.

The fixes are effectively dropping the usage of ipc to communicate
status, using polling on the hda stream, and having a formatter per call
context (cores + isr) when log mode immediate is enabled to fix log
mangling. However it was found this had a lot of unintentional side
effects that made it difficult to make progress on when it came to
changes of the host side python tooling.

Meanwhile the feature has sat unused for nearly a year. Remove it, and
it can always be revisited in the future if something like it happens to
be needed.

Signed-off-by: Tom Burdick <thomas.burdick@intel.com>