md: don't clear curr_resync_completed at end of resync.

There is no need to set this to zero at this point.  It will be
set to zero by remove_and_add_spares or at the start of
md_do_sync at the latest.
And setting it to zero before MD_RECOVERY_RUNNING is cleared can
make a 'zero' appear briefly in the 'sync_completed' sysfs attribute
just as resync is finishing.

So simply remove this setting to zero.
Signed-off-by: NeilBrown <neilb@suse.de>

drivers/md/md.c

@@ -6984,9 +6984,6 @@ void md_do_sync(mddev_t *mddev)
 	} else if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
 		mddev->resync_min = mddev->curr_resync_completed;
 	mddev->curr_resync = 0;
-	if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery))
-		mddev->curr_resync_completed = 0;
-	sysfs_notify(&mddev->kobj, NULL, "sync_completed");
 	wake_up(&resync_wait);
 	set_bit(MD_RECOVERY_DONE, &mddev->recovery);
 	md_wakeup_thread(mddev->thread);