audio: add wakelock capability for audiohalservice

1. wake_lock group
2. BLOCK_SUSPEND capability

int pm_wake_lock(const char *buf)
{
	const char *str = buf;
	struct wakelock *wl;
	u64 timeout_ns = 0;
	size_t len;
	int ret = 0;

	if (!capable(CAP_BLOCK_SUSPEND))
		return -EPERM;
Bug: 111018819
Test: manual
Change-Id: I1283e4b1ab2b95e4e94df045240001485593f1ab
Signed-off-by: Carter Hsu <carterhsu@google.com>
diff --git a/audio/common/all-versions/default/service/android.hardware.audio@2.0-service.rc b/audio/common/all-versions/default/service/android.hardware.audio@2.0-service.rc
index 8217b94..6e91bcc 100644
--- a/audio/common/all-versions/default/service/android.hardware.audio@2.0-service.rc
+++ b/audio/common/all-versions/default/service/android.hardware.audio@2.0-service.rc
@@ -2,7 +2,8 @@
     class hal
     user audioserver
     # media gid needed for /dev/fm (radio) and for /data/misc/media (tee)
-    group audio camera drmrpc inet media mediadrm net_bt net_bt_admin net_bw_acct
+    group audio camera drmrpc inet media mediadrm net_bt net_bt_admin net_bw_acct wakelock
+    capabilities BLOCK_SUSPEND
     ioprio rt 4
     writepid /dev/cpuset/foreground/tasks /dev/stune/foreground/tasks
     # audioflinger restarts itself when it loses connection with the hal