ixgbe: Avoid needless PHY access on copper phys

Avoid a needless PHY access on copper phys to save the 10ms wait
time for each PHY access. A helper function is introduced to
actually do the register access and process the contents.

Signed-off-by: Mark Rustad <mark.d.rustad@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>