Don't hardcode ceph.com mirror for linux-firmware
Don't hardcode ceph.com mirror for linux-firmware

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