[Trivial] Clarify conditions under which power recovery is attempted
[Trivial] Clarify conditions under which power recovery is attempted

Be more precise when describing the conditions for automatic
recovery from power failures ('maintenance type' is a term
we use nowhere else).

Change-Id: Iaf14c0fc73f8c97b9d8669485011966a650c21a8

openstack/ironic,openstack/ironic