fix create_pool_with_unique_name call to use profile name

It has been tested manually successfully with http://qa-proxy.ceph.com/teuthology/teuthology-2014-07-01_02:30:37-rados-firefly-distro-basic-plana/336732/orig.config.yaml
<pre>
...
  description: rados/singleton/{all/ec-lost-unfound.yaml fs/btrfs.yaml msgr-failures/few.yaml}
...
2014-07-02 19:51:35,864.864 INFO:teuthology.orchestra.run.mira028:Running: 'adjust-ulimits ceph-coverage /home/ubuntu/cephtest/archive/coverage ceph osd erasure-code-profile set lost_unfound k=2 m=2 ruleset-failure-domain=osd'
2014-07-02 19:51:36,710.710 INFO:teuthology.task.ec_lost_unfound.ceph_manager:creating pool_name unique_pool_0
2014-07-02 19:51:36,710.710 INFO:teuthology.orchestra.run.mira028:Running: 'adjust-ulimits ceph-coverage /home/ubuntu/cephtest/archive/coverage ceph osd pool create unique_pool_0 16 16 erasure lost_unfound'
2014-07-02 19:51:38,738.738 INFO:teuthology.orchestra.run.mira028.stderr:pool 'unique_pool_0' created
...
2014-07-02 19:57:44,491.491 INFO:teuthology.run:Summary data:
{duration: 585.1162419319153, flavor: basic, owner: loic@dachary.org, success: true}
</pre>