mirror/ubuntu/boot: patch only the upstream initrd
mirror/ubuntu/boot: patch only the upstream initrd

The initrd downloaded from an fwm mirror already has the necessary
patches applied, an attempt to apply the patch(es) once more is deemed
to fail and breaks the build. Therefore patch/repack only the upstream
initrd.gz (i.e. when USE_MIRROR=none)

Closes-Bug: #1412778
Change-Id: I1b1532751492648305cea873f9e9627bdaf2908c

ddepaoli3/fuel-main-dev,zhaochao/fuel-main,eayunstack/fuel-main,ddepaoli3/fuel-main-dev,Fiware/ops.Fuel-main-dev,stackforge/fuel-main,teselkin/fuel-main,SmartInfrastructures/fuel-main-dev,AnselZhangGit/fuel-main,AnselZhangGit/fuel-main,eayunstack/fuel-main,ddepaoli3/fuel-main-dev,SergK/fuel-main,ddepaoli3/fuel-main-dev,Fiware/ops.Fuel-main-dev,dancn/fuel-main-dev,SmartInfrastructures/fuel-main-dev,eayunstack/fuel-main,AnselZhangGit/fuel-main,SmartInfrastructures/fuel-main-dev,SergK/fuel-main,teselkin/fuel-main,huntxu/fuel-main,huntxu/fuel-main,dancn/fuel-main-dev,SergK/fuel-main,dancn/fuel-main-dev,teselkin/fuel-main,stackforge/fuel-main,teselkin/fuel-main,huntxu/fuel-main,zhaochao/fuel-main,Fiware/ops.Fuel-main-dev,zhaochao/fuel-main,zhaochao/fuel-main,SmartInfrastructures/fuel-main-dev,stackforge/fuel-main,AnselZhangGit/fuel-main,dancn/fuel-main-dev,Fiware/ops.Fuel-main-dev,zhaochao/fuel-main