soc/mediatek/adsp: Enable winstream console

Enable a winstream console via the new "STATIC" platform API, and add
code to the loader script to read it (largely cribbed with
modifications from the same feature in cavstool.py, we have nowhere to
share code like this, alas).

The older logging feature is still present as an "oldlog" mode to the
script.  We can leave it for a bit as a failsafe (e.g. for debugging
issues with winstream) and remove it later.

Signed-off-by: Andy Ross <andyross@google.com>