pci: cleanup failover sanity check

pci: cleanup failover sanity check

Commit a1190ab628 has added a "allow_unplug_during_migration = true" at
the end of the main "if" block, so it is not needed to set it anymore
in the previous checking.

Remove it, to have only sub-ifs that check for needed conditions and exit
if one fails.

Fixes: 4f5b6a05a4e7 ("pci: add option for net failover")
Fixes: a1190ab628c0 ("migration: allow unplug during migration for failover devices")
Cc: jfreimann@redhat.com
Signed-off-by: Laurent Vivier <lvivier@redhat.com>
Message-Id: <20210212135250.2738750-2-lvivier@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Jens Freimann <jfreimann@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>