e1000e: cleanup e1000_init_mac_params_80003es2lan()

Combine two switch statements into one, convert a nebulous pointer to one
that is a bit more in keeping with the rest of the driver code and remove
some dead code (there are no 80003es2lan devices with fiber).  No change in
functionality, just cosmetic changes.

Signed-off-by: Bruce Allan <bruce.w.allan@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>