There are some lines could be removed due to recent
change for raid1 such as commit 3956df15d634 ("md:
move suspend_hi/lo handling into core md code").

Also, seems some comments are put to wrong place,
move them before wait_barrier.
Signed-off-by: NGuoqing Jiang <gqjiang@suse.com>
Signed-off-by: NShaohua Li <shli@fb.com>