engine: Auto recovery ignores hosts with problematic NICs

Such hosts cannot be automatically recovered since the NICs are down and
the host will just go back to non-operational state.

Change-Id: I70bff4ba5541156c31fb8afdd38ff6f706c0d869
Bug-Url: https://bugzilla.redhat.com/953115
Signed-off-by: Mike Kolesnik <mkolesni@redhat.com>