ALSA: timer: Use deferred fasync helper

[ Upstream commit 95cc637c1afd83fb7dd3d7c8a53710488f4caf9c ]

For avoiding the potential deadlock via kill_fasync() call, use the
new fasync helpers to defer the invocation from PCI API.  Note that
it's merely a workaround.

Reported-by:  <syzbot+1ee0910eca9c94f71f25@syzkaller.appspotmail.com>
Reported-by:  <syzbot+49b10793b867871ee26f@syzkaller.appspotmail.com>
Reported-by:  <syzbot+8285e973a41b5aa68902@syzkaller.appspotmail.com>
Link: https://lore.kernel.org/r/20220728125945.29533-3-tiwai@suse.de


Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>