autotest/virt-test — pull request #686 by humanux (2013-07-29 08:00:41+00:00)
Title:  virttest.utils_net : modify the method of get_linux_ifname

This patch modify the method of get_linux_ifname.
if the mac_address is assigned will return the nic interface
with the assigned mac_address, else, will return a list contain
all the nic interfaces, except "lo"

Signed-off-by: Yunping Zheng