ice: remove unnecessary virtchnl_ether_addr struct use

The dev_lan_addr and hw_lan_addr members of ice_vf are used only to store
the MAC address for the VF. They are defined using virtchnl_ether_addr, but
only the .addr sub-member is actually used. Drop the use of
virtchnl_ether_addr and just use a u8 array of length [ETH_ALEN].

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Marek Szlosek <marek.szlosek@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>