Normalize MAC addresses from mac_pool generator

The addresses from mac_pool generator were not sanitized so any address
containing some letter would fail comparison check because of case
sensitivity. I used normalize_hwaddr() function that we used globally
in the code for hardware address manipulation.

Signed-off-by: Jan Tluka <jtluka@redhat.com>
Signed-off-by: Jiri Pirko <jiri@resnulli.us>