Access debug slot directly using cavstool.py, by specifying the debug
slot number where the debug_stream data is transferred.

Adds one command line parameter for selecting the debug slot directly
and adds an alternative mainloop for polling the slot through
cavstool.py direct access.

The commit also adds quite a few data consistency checks and error
handling improvements as with the direct memory access its much more
likely to get inconsistent data when the DSP is booting up, and code
needs to be robust enough not to crash in such a situation. Also the
logging messages about those checks failing has been lowered so that
they are not too noisy.

Signed-off-by: Jyri Sarha <[email protected]>

Add overlay to build debug_stream protocol over a debug window slot,
make room for the slot, and send thread info data through it.

Signed-off-by: Jyri Sarha <[email protected]>

A simple typo fix to a logging message.

Signed-off-by: Jyri Sarha <[email protected]>