ALSA: firewire-motu: add missing entries to Kconfig

MOTU Traveler and Audio Express are supported as well.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/firewire/Kconfig

@@ -147,7 +147,9 @@ config SND_FIREWIRE_MOTU
 	help
 	 Say Y here to enable support for FireWire devices which MOTU produced:
 	  * 828mk2
+	  * Traveler
 	  * 828mk3
+	  * Audio Express
 
 	 To compile this driver as a module, choose M here: the module
 	 will be called snd-firewire-motu.