nic_hotplug.one_pci.nic_e1000: small fix to the escape character

Signed-off-by: Cong Li <coli@redhat.com>
Merge pull request #1668 from CongSmile/nic_hotplug.one_pci.nic_e1000

nic_hotplug.one_pci.nic_e1000: small fix to the escape character