ALSA: ctxfi: Swapped SURROUND-SIDE channels on emu20k2

On Soundblaster X-FI Titanium with emu20k2 the SIDE and SURROUND
channels were swapped and wrong. 
I double checked it with connector colors and creative soundblaster
windows drivers.

So I swapped them to the true order.
Now "speaker-test -c6" and "speaker-test -c8" are working fine.

Signed-off-by: Frank Roth <frashman@freenet.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>