ALSA: line6: Add support for POD X3

This includes audio in/out and basic initialization via control EP (emulates
what original driver does). The initialization is done similarly to original
POD, firmware and serial IDs are read and exported via sysfs.
Signed-off-by: Andrej Krutak <dev@andree.sk>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/usb/line6/Kconfig

@@ -21,10 +21,10 @@ config SND_USB_POD
 	      re-amping)
 
 config SND_USB_PODHD
-	tristate "Line 6 POD HD300/400/500 USB support"
+	tristate "Line 6 POD X3/HD300/400/500 USB support"
 	select SND_USB_LINE6
 	help
-	  This is a driver for POD HD300, 400 and 500 devices.
+	  This is a driver for POD X3, HD300, 400 and 500 devices.
 
 config SND_USB_TONEPORT
 	tristate "TonePort GX, UX1 and UX2 USB support"