Fix do_commit() behavior

Commit 751c6a17 changed the monitor's
'commit' command to this behavior:

1. Any string you type as argument will cause do_commit() to
call bdrv_commit() to all devices

2. If you enter a device name, it will be the only one ignored
by do_commit() :)

The fix is to call bdrv_commit() to the specified device only and
ignore the others (when 'all' is not specified).
Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>
Message-Id: 

monitor.c

@@ -259,7 +259,7 @@ static void do_commit(Monitor *mon, const char *device)
     all_devices = !strcmp(device, "all");
     TAILQ_FOREACH(dinfo, &drives, next) {
         if (!all_devices)
-            if (!strcmp(bdrv_get_device_name(dinfo->bdrv), device))
+            if (strcmp(bdrv_get_device_name(dinfo->bdrv), device))
                 continue;
         bdrv_commit(dinfo->bdrv);
     }