ALSA: line6: Split to each driver

Split to each individual driver for POD, PODHD, TonePort and Variax
with a core LINE6 helper module.  The new modules follow the standard
ALSA naming rule with snd prefix: snd-usb-pod, snd-usb-podhd,
snd-usb-toneport and snd-usb-variax, together with the corresponding
CONFIG_SND_USB_* Kconfig items.

Tested-by: Chris Rorvick <chris@rorvick.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/usb/Makefile b/sound/usb/Makefile
index 54045b7..2d2d122 100644
--- a/sound/usb/Makefile
+++ b/sound/usb/Makefile
@@ -25,4 +25,4 @@
 obj-$(CONFIG_SND_USB_US122L) += snd-usbmidi-lib.o
 
 obj-$(CONFIG_SND) += misc/ usx2y/ caiaq/ 6fire/ hiface/ bcd2000/
-obj-$(CONFIG_LINE6_USB)		+= line6/
+obj-$(CONFIG_SND_USB_LINE6)	+= line6/