Kernel features for USB host mode audio

Change-Id: I9ea46f6dab2f39c8b7e70c1f6374a529c2e379e8
diff --git a/src/devices/tech/kernel.jd b/src/devices/tech/kernel.jd
index da749c5..637c5c4 100644
--- a/src/devices/tech/kernel.jd
+++ b/src/devices/tech/kernel.jd
@@ -288,3 +288,11 @@
 CONFIG_TIMER_STATS=y
 CONFIG_SCHED_TRACER=y
 </pre>
+
+<h3>For USB host mode audio</h3>
+
+<pre>
+CONFIG_SND_USB=y
+CONFIG_SND_USB_AUDIO=y
+# CONFIG_USB_AUDIO is for a peripheral mode (gadget) driver
+</pre>