task/ceph: Fix device list
task/ceph: Fix device list

dict.items() returns a tuple, whereas we want
the values().

Signed-off-by: Sam Lang <70ab3b98ad075c66e7d3501cb42b80a7e41da316@inktank.com>

tchaikov/teuthology,robbat2/teuthology,ivotron/teuthology,t-miyamae/teuthology,dmick/teuthology,ceph/teuthology,SUSE/teuthology,dreamhost/teuthology,caibo2014/teuthology,dmick/teuthology,dmick/teuthology,michaelsevilla/teuthology,SUSE/teuthology,ceph/teuthology,zhouyuan/teuthology,ktdreyer/teuthology,yghannam/teuthology,michaelsevilla/teuthology,zhouyuan/teuthology,t-miyamae/teuthology,robbat2/teuthology,ivotron/teuthology,ktdreyer/teuthology,tchaikov/teuthology,SUSE/teuthology,yghannam/teuthology,caibo2014/teuthology,dreamhost/teuthology