ALSA: virtuoso: add one more headphone impedance setting

Add one more option to the "Headphones Impedance" control to synchronize
with recent versions of the Windows driver.

Tested-by: fugazzi® <fugazzi99@gmail.com>
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>