kni: more compatibility with RHEL 6.4/6.5

kni: more compatibility with RHEL 6.4/6.5

For RH 6.5:
- always include mdio.h to get the definitions of MDIO_EEE, ETHTOOL_GEEE
- is_link_local_ether_addr(), pcie_capability_clear_and_set_word(),  and
  ether_addr_equal() have been backported

For RH 6.4:
- same issue with ether_addr_equal()
- here ETH_GEE is defined without having the functions.

igb_ethtool.c:2441: error: implicit declaration of function ‘mmd_eee_adv_to_ethtool_adv_t’

Signed-off-by: Jean-Mickael Guerin <jean-mickael.guerin@6wind.com>
Acked-by: Thomas Monjalon <thomas.monjalon@6wind.com>