storage: Fix startup issue for logical pool
storage: Fix startup issue for logical pool

Commit id '71b803ac' assumed that the storage pool source device path
was required for a 'logical' pool. This resulted in a failure to start
a pool without any device path defined.

So, adjust the virStorageBackendLogicalMatchPoolSource logic to
return success if at least the pool name matches the vgs output
when no pool source device path is/are provided.

datto/libvirt,crobinso/libvirt,fabianfreyer/libvirt,eskultety/libvirt,eskultety/libvirt,nertpinx/libvirt,taget/libvirt,VenkatDatta/libvirt,libvirt/libvirt,jardasgit/libvirt,libvirt/libvirt,andreabolognani/libvirt,zippy2/libvirt,jardasgit/libvirt,jardasgit/libvirt,crobinso/libvirt,VenkatDatta/libvirt,libvirt/libvirt,nertpinx/libvirt,jardasgit/libvirt,VenkatDatta/libvirt,datto/libvirt,jardasgit/libvirt,zippy2/libvirt,eskultety/libvirt,taget/libvirt,fabianfreyer/libvirt,fabianfreyer/libvirt,datto/libvirt,nertpinx/libvirt,fabianfreyer/libvirt,jfehlig/libvirt,jfehlig/libvirt,zippy2/libvirt,libvirt/libvirt,andreabolognani/libvirt,rlaager/libvirt,rlaager/libvirt,rlaager/libvirt,rlaager/libvirt,fabianfreyer/libvirt,eskultety/libvirt,crobinso/libvirt,olafhering/libvirt,andreabolognani/libvirt,jfehlig/libvirt,eskultety/libvirt,taget/libvirt,VenkatDatta/libvirt,zippy2/libvirt,datto/libvirt,taget/libvirt,datto/libvirt,andreabolognani/libvirt,VenkatDatta/libvirt,crobinso/libvirt,nertpinx/libvirt,nertpinx/libvirt,jfehlig/libvirt,taget/libvirt,rlaager/libvirt,olafhering/libvirt,olafhering/libvirt,olafhering/libvirt,andreabolognani/libvirt