kernel: usb-audio remove Kconfig USB_AUDIO

CONFIG_USB_AUDIO is a "USB Audio Gadget" driver, not a usb device driver

CONFIG_USB_AUDIO is "USB Audio support" before linux 2.6

Signed-off-by: Liangbin Lian <[email protected]>

package/kernel/linux/modules/usb.mk

@@ -534,7 +534,6 @@ $(eval $(call KernelPackage,usb-wdm))
 define KernelPackage/usb-audio
   TITLE:=Support for USB audio devices
   KCONFIG:= \
-	CONFIG_USB_AUDIO \
 	CONFIG_SND_USB=y \
 	CONFIG_SND_USB_AUDIO
   $(call AddDepends/usb)