e1000e: fix .ndo_set_rx_mode for 82579

Secondary unicast and multicast addresses are added to the Receive
Address registers (RAR) for most parts supported by the driver.  For
82579, there is only one actual RAR and a number of Shared Receive Address
registers (SHRAR) that are shared among the driver and f/w which can be
reserved and write-protected by the f/w.  On this device, use the SHRARs
that are not taken by f/w for the additional addresses.

Add a MAC ops function pointer infrastructure (similar to other MAC
operations in the driver) for setting RARs, introduce a new rar_set
function for 82579 and convert the existing code that sets RARs on other
devices to a generic rar_set function.

Signed-off-by: Bruce Allan <bruce.w.allan@intel.com>
Tested-by: Jeff Pieper <jeffrey.e.pieper@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>