bug 212960 - alsa: fix locking problem in snd_device_new

[Leann Ogasawara]

Hi Guys,

saa7134-alsa and cx88-alsa were recently enabled in lum:

https://bugs.launchpad.net/ubuntu/+bug/202065
https://bugs.launchpad.net/ubuntu/+bug/201431

These however trigger a kernel oops that's been reported in:

https://bugs.launchpad.net/ubuntu/+bug/212100
https://bugs.launchpad.net/ubuntu/+bug/212271

Crimsun pointed me to the following report which contains a patch to
resolve the oops:

https://bugs.launchpad.net/ubuntu/+source/linux-ubuntu-modules-2.6.24/+bug/212960

Care to review?

Thanks,
Leann