md: MD_RECOVERY_NEEDED is set for mddev->recovery

commit 82a301cb0ea2df8a5c88213094a01660067c7fb4 upstream.

Fixes: 90f5f7ad("md: Wait for md_check_recovery before attempting device
removal.")

Reviewed-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>