audio: honor QEMU_AUDIO_TIMER_PERIOD instead of waking up every *nano* second

Now that we no longer have MIN_REARM_TIMER_NS a bug in the audio subsys has
clearly shown it self by trying to make a timer fire every nano second.

Note we have a similar problem in 1.6, 1.5 and older but there
MIN_REARM_TIMER_NS limits the wakeups caused by audio being active to
4000 times / second. This still causes a host cpu load of 50 % for simply
playing audio, where as with this patch git master is at 13%, so we should
backport this to 1.5 and 1.6 too.

Note this will not apply to 1.5 and 1.6 as is.

Cc: qemu-stable@nongnu.org
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
(cherry picked from commit b4350deed6)

Conflicts:

	audio/audio.c

*fixed to reflect 1.6 timer function/clock names

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

audio/audio.c

@@ -1124,7 +1124,8 @@ static int audio_is_timer_needed (void)
 static void audio_reset_timer (AudioState *s)
 {
     if (audio_is_timer_needed ()) {
-        qemu_mod_timer (s->ts, qemu_get_clock_ns (vm_clock) + 1);
+        qemu_mod_timer (s->ts,
+            qemu_get_clock_ns(vm_clock) + conf.period.ticks);
     }
     else {
         qemu_del_timer (s->ts);