Bluetooth samples: Add USB Audio to Broadcast Sink sample

Added USB Audio output for the Broadcast Sink sample. In addition
offloading of the LC3 codec was also made. The sample supports only
mono, and a KConfig option was added to configure which audio
location to sync to.

Signed-off-by: Fredrik Danebjer <frdn@demant.com>

samples/bluetooth/broadcast_audio_sink/Kconfig

@@ -43,4 +43,25 @@ config ENABLE_LC3
 	select LIBLC3
 	select FPU
 
+config USE_USB_AUDIO_OUTPUT
+	bool "Use USB Audio as output"
+	depends on ENABLE_LC3
+	select USB_DEVICE_STACK
+	select USB_DEVICE_AUDIO
+	select RING_BUFFER
+	help
+	  Enables USB audio as output as a USB peripheral. This does not support providing USB
+	  audio to e.g. speakers that are also USB peripherals, but can be connected to e.g. a
+	  phone or PC as a USB-in device (such as a USB microphone).
+	  USB audio only supports a single audio channel.
+
+config TARGET_BROADCAST_CHANNEL
+	int "Broadcast Channel Audio Location to sync to"
+	range 0 2
+	default 1
+	depends on USE_USB_AUDIO_OUTPUT
+	help
+	  Channel Audio Location to sync to. These corresponds to the bt_audio_location,
+	  supporting mono, left and right channels
+
 source "Kconfig.zephyr"

samples/bluetooth/broadcast_audio_sink/boards/nrf5340_audio_dk_nrf5340_cpuapp.conf

@@ -1,3 +1,7 @@
 # The LC3 codec uses a large amount of stack. This app runs the codec in the work-queue, hence
 # inctease stack size for that thread.
 CONFIG_SYSTEM_WORKQUEUE_STACK_SIZE=4096
+CONFIG_ENABLE_LC3=y
+CONFIG_TARGET_BROADCAST_CHANNEL=1
+CONFIG_USE_USB_AUDIO_OUTPUT=y
+CONFIG_USB_DEVICE_PRODUCT="USB Broadcast Sink"