If mdcheck_start service can finish check action, it doesn't need to start mdcheck_continue
service. So in rhel only patch mdcheck.patch, we stop mdcheck_continue timer.

And there is a history problem. It needed KillMode=none before, so it removed
the upstream patch 52c67fcdd. Now this problem has been fixed, so we can do the
backport more easilly now. We don't need to remove the upstream patch here again.

Resolves: rhbz#2116418, rhbz#2150862, rhbz#2159584

Signed-off-by: Xiao Ni <xni@redhat.com>