migration: expose the bitmap_sync_count to the end

expose the count that logs the times of updating the dirty bitmap to
end user.

Signed-off-by: ChenLiang <chenliang88@huawei.com>
Signed-off-by: Gonglei <arei.gonglei@huawei.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
diff --git a/qapi-schema.json b/qapi-schema.json
index 0b00427..7b95039 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -651,13 +651,15 @@
 #
 # @mbps: throughput in megabits/sec. (since 1.6)
 #
+# @dirty-sync-count: number of times that dirty ram was synchronized (since 2.1)
+#
 # Since: 0.14.0
 ##
 { 'type': 'MigrationStats',
   'data': {'transferred': 'int', 'remaining': 'int', 'total': 'int' ,
            'duplicate': 'int', 'skipped': 'int', 'normal': 'int',
            'normal-bytes': 'int', 'dirty-pages-rate' : 'int',
-           'mbps' : 'number' } }
+           'mbps' : 'number', 'dirty-sync-count' : 'int' } }
 
 ##
 # @XBZRLECacheStats