ALSA: hda - Add reboot notifier

commit 0cbf00980f0fc4cc064a15ab3dfce19b5fae9130 upstream

The current snd-hda-intel driver seems blocking the power-off on some
devices like eeepc.  Although this is likely a BIOS problem, we can add
a workaround by disabling IRQ lines before power-off operation.
This patch adds the reboot notifier to achieve it.

The detailed problem description is found in bug#11889:
    http://bugme.linux-foundation.org/show_bug.cgi?id=11889

Tested-by: Luiz Fernando N. Capitulino <lcapitulino@mandriva.com.br>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>