tools include UAPI: Sync sound/asound.h copy with the kernel sources

Picking the changes from:

  81be1093 ("ALSA: pcm: Add SNDRV_PCM_INFO_EXPLICIT_SYNC flag")

Which entails no changes in the tooling side as it doesn't introduce new
ioctls.

To silence this perf tools build warning:

  Warning: Kernel ABI header at 'tools/include/uapi/sound/asound.h' differs from latest version at 'include/uapi/sound/asound.h'
  diff -u tools/include/uapi/sound/asound.h include/uapi/sound/asound.h

Cc: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/include/uapi/sound/asound.h

@@ -299,6 +299,7 @@ typedef int __bitwise snd_pcm_subformat_t;
 #define SNDRV_PCM_INFO_HAS_LINK_ABSOLUTE_ATIME     0x02000000  /* report absolute hardware link audio time, not reset on startup */
 #define SNDRV_PCM_INFO_HAS_LINK_ESTIMATED_ATIME    0x04000000  /* report estimated link audio time */
 #define SNDRV_PCM_INFO_HAS_LINK_SYNCHRONIZED_ATIME 0x08000000  /* report synchronized audio/system time */
+#define SNDRV_PCM_INFO_EXPLICIT_SYNC	0x10000000	/* needs explicit sync of pointers and data */
 
 #define SNDRV_PCM_INFO_DRAIN_TRIGGER	0x40000000		/* internal kernel flag - trigger in drain */
 #define SNDRV_PCM_INFO_FIFO_IN_FRAMES	0x80000000	/* internal kernel flag - FIFO size is in frames */