Enable EAPD bit on Thinkpad X61/T61.  The recent model requires it
explicitly to make any sounds.   In future, it should be toggled
automatically on demand.
Also, added a beep volume/switch.  Some people like it although I
don't understand why :)
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>