greybus: audio: don't inclide rwlock.h directly.

rwlock.h should not be included directly. Instead linux/splinlock.h
should be included. One thing it does is to break the RT build.

Cc: Vaibhav Agarwal <vaibhav.sr@gmail.com>
Cc: Johan Hovold <johan@kernel.org>
Cc: Alex Elder <elder@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: greybus-dev@lists.linaro.org
Cc: devel@driverdev.osuosl.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Mark Greer <mgreer@animalcreek.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/greybus/audio_manager.c

@@ -10,7 +10,7 @@
 #include <linux/sysfs.h>
 #include <linux/module.h>
 #include <linux/init.h>
-#include <linux/rwlock.h>
+#include <linux/spinlock.h>
 #include <linux/idr.h>
 
 #include "audio_manager.h"