ALSA: Add hrtimer backend for ALSA timer interface

Added the hrtimer backend for ALSA timer interface.
It can be used for the sequencer timer source.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/include/sound/asound.h b/include/sound/asound.h
index 2c4dc90..1c02ed1 100644
--- a/include/sound/asound.h
+++ b/include/sound/asound.h
@@ -575,6 +575,7 @@
 #define SNDRV_TIMER_GLOBAL_SYSTEM	0
 #define SNDRV_TIMER_GLOBAL_RTC		1
 #define SNDRV_TIMER_GLOBAL_HPET		2
+#define SNDRV_TIMER_GLOBAL_HRTIMER	3
 
 /* info flags */
 #define SNDRV_TIMER_FLG_SLAVE		(1<<0)	/* cannot be controlled */