[ALSA] ad1848: replace HZ calculus with msecs_to_jiffies()

If I'm not mistaken, any (new) use of HZ these days is considered a bug so
while I'm there...

Signed-off-by: Rene Herman <rene.herman@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>