[ALSA] hda-intel - Fix pci_disable_msi() call

Fix the order to call pci_disable_msi() to be after free_irq().
(Otherwise pci_disable_msi() bugs you.)
Also, added a description of disable_msi option to documentation.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>