Merge pull request #771 from CongLi/virtio_win

qemu.tests.single_driver_install: Update virtio serial device name for different hosts.

qemu/tests/cfg/single_driver_install.cfg

@@ -56,6 +56,8 @@
             remove_image_stg = yes
         - with_vioserial:
             driver_name = vioser
+            device_name = "VirtIO Serial Driver"
+            Host_RHEL.m6, Host_RHEL.m7.u0, Host_RHEL.m7.u1, Host_RHEL.m7.u2:
                 device_name = "VirtIO-Serial Driver"
             virtio_ports = "vs"
             virtio_port_type = serialport