usb: gadget: Kconfig: enable separate compilation of uac1/uac2 functions

uac1 and uac2 functions are available through the configfs interface
and it should be possible to build them without building their legacy
gadgets.
Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/gadget/Kconfig

@@ -362,6 +362,37 @@ config USB_CONFIGFS_F_FS
 	  implemented in kernel space (for instance Ethernet, serial or
 	  mass storage) and other are implemented in user space.
 
+config USB_CONFIGFS_F_UAC1
+	boolean "Audio Class 1.0"
+	depends on USB_CONFIGFS
+	depends on SND
+	select USB_LIBCOMPOSITE
+	select SND_PCM
+	select USB_F_UAC1
+	help
+	  This Audio function implements 1 AudioControl interface,
+	  1 AudioStreaming Interface each for USB-OUT and USB-IN.
+	  This driver requires a real Audio codec to be present
+	  on the device.
+
+config USB_CONFIGFS_F_UAC2
+	boolean "Audio Class 2.0"
+	depends on USB_CONFIGFS
+	depends on SND
+	select USB_LIBCOMPOSITE
+	select SND_PCM
+	select USB_F_UAC2
+	help
+	  This Audio function is compatible with USB Audio Class
+	  specification 2.0. It implements 1 AudioControl interface,
+	  1 AudioStreaming Interface each for USB-OUT and USB-IN.
+	  This driver doesn't expect any real Audio codec to be present
+	  on the device - the audio streams are simply sinked to and
+	  sourced from a virtual ALSA sound card created. The user-space
+	  application may choose to do whatever it wants with the data
+	  received from the USB Host and choose to provide whatever it
+	  wants as audio data to the USB Host.
+
 source "drivers/usb/gadget/legacy/Kconfig"
 
 endchoice