qemuBuildMemoryBackendProps: use 'rc' instead of ret.
qemuBuildMemoryBackendProps: use 'rc' instead of ret.

Do not overwrite the 'ret' value more than once.

Signed-off-by: Ján Tomko <4cab11cfb98d3c937327354a78eb07dbb6ee2bc6@redhat.com>
Reviewed-by: Cole Robinson <7cd45ff6ad1fb7cf556a02797d774247851499f8@redhat.com>

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