If we cannot create the ALSA mixer, it is a good reason to fail to
load the volume subdriver, and not to fail to load the entire module.

While at it, add more debugging messages, as the error paths are being
used a lot more than I'd expect, and it is failing to set up the ALSA
mixer on a number of ThinkPads.
Reported-by: NPeter Jordan <usernetwork@gmx.info>
Signed-off-by: NHenrique de Moraes Holschuh <hmh@hmh.eng.br>
Signed-off-by: NLen Brown <len.brown@intel.com>