virt_win_reg: use localhost as the remote end for remote testing.

As we can use localhost as a fake remote for remote testing, there
is no need to require another host.

Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com>
virt_win_reg: Do not use the ComputerName in reg.

Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com>