ixgbe: Drop unused code for setting up unicast addresses

This change removes the unused code that was setting up the uc_addr_list.

Signed-off-by: Emil Tantilov <emil.s.tantilov@intel.com>
Tested-by: Stephen Ko <stephen.s.ko@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>