Split the flush_merge fields from sm_i, and use the new struct flush_cmd_control
to wrap it, so that we can igonre these fileds if flush_merge is disable, and
it alse can the structs more neat.
Signed-off-by: NGu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: NJaegeuk Kim <jaegeuk.kim@samsung.com>