[ALSA] soc - ln2440sbc ac97 support

This patch adds ac97 support for ln2440sbc board from LittleChips.
This board is based on s3c2440 SoC + AC97 Realtek ALC650 codec.
Existing s3c2443 implementation is slightly modified because s3c2440
and s3c2443 have different AC97 interrupts.

Signed-off-by: Ivan Kuten <ivan.kuten@promwad.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>