[ALSA] doc - Remove IRQF_DISABLED from the example description

Remove the bogus IRQF_DISBLAED together with IRQF_SHARED from the
example code in the document.

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