Been tested on each major revision that's relevant here, but I'm sure there
are still bugs waiting to be ironed out.

This is a *very* invasive change.

There's a couple of pieces left that I don't like much (eg. other engines
using fifo_priv for the channel count), but that's an artefact of there
being a master channel list still.  This is changing, slowly.
Signed-off-by: NBen Skeggs <bskeggs@redhat.com>

Uncertain if/how the hw does multiple PMPEG channels, supporting one is
better than none however.
Signed-off-by: NBen Skeggs <bskeggs@redhat.com>

Signed-off-by: NBen Skeggs <bskeggs@redhat.com>

It may not be necessary to fail in certain cases (such as failing to idle)
on module unload, whereas on suspend it's important to ensure a consistent
state can be restored on resume.
Signed-off-by: NBen Skeggs <bskeggs@redhat.com>

Signed-off-by: NBen Skeggs <bskeggs@redhat.com>