This adds "LPBK" buttons to the output strip
channels for toggling the hardware output
loopback functionality recently added for
HDSP9632.
The preset data is just appended to the
preset file so that it can still be loaded
in older versions.
Merged the work by Florian Faber that's distributed separately as
hdspmixer64.
Code taken from http://wiki.linuxproaudio.org/index.php/App:hdspmixer_64
Signed-off-by: Adrian Knoth <adi@drcomp.erfurt.thur.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
