qemu: domain: Process only one object in qemuDomainPrepareDiskSourceTLS
qemu: domain: Process only one object in qemuDomainPrepareDiskSourceTLS

Remove the loop from qemuDomainPrepareDiskSourceTLS and rename it to
qemuDomainPrepareStorageSourceTLS. Currently there is no backing chain
to prepare so fixing one device is equivalent. In the future it will be
reused in a function which will do the looping.

Signed-off-by: Peter Krempa <2cf5c04c61aa466e4a47bfedc747d17279c72ffc@redhat.com>
Reviewed-by: Ján Tomko <4cab11cfb98d3c937327354a78eb07dbb6ee2bc6@redhat.com>

libvirt/libvirt,fabianfreyer/libvirt,fabianfreyer/libvirt,crobinso/libvirt,olafhering/libvirt,libvirt/libvirt,eskultety/libvirt,jardasgit/libvirt,olafhering/libvirt,libvirt/libvirt,zippy2/libvirt,zippy2/libvirt,jfehlig/libvirt,fabianfreyer/libvirt,nertpinx/libvirt,nertpinx/libvirt,andreabolognani/libvirt,jfehlig/libvirt,jardasgit/libvirt,nertpinx/libvirt,fabianfreyer/libvirt,olafhering/libvirt,jfehlig/libvirt,libvirt/libvirt,nertpinx/libvirt,andreabolognani/libvirt,zippy2/libvirt,eskultety/libvirt,jfehlig/libvirt,crobinso/libvirt,andreabolognani/libvirt,jardasgit/libvirt,olafhering/libvirt,zippy2/libvirt,fabianfreyer/libvirt,eskultety/libvirt,andreabolognani/libvirt,jardasgit/libvirt,eskultety/libvirt,crobinso/libvirt,eskultety/libvirt,andreabolognani/libvirt,jardasgit/libvirt,crobinso/libvirt,nertpinx/libvirt