[ALSA] Modem support for ALI5451

ALI5451 driver
This patch adds modem support for ali5451. Since it is same pci device
all is done in ali5451.c.
Signed-off-by: Sasha Khapyorsky <sashak@smlink.com>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>