e1000e: read of PHY register may access wrong page on 82578

Remove unnecessary workaround that mistakenly does not perform a page
select operation for PHY registers 29 and 30 (assuming these are the PHY
debug port address and data registers) on 82578 which can cause reads
of the Transmit with No Carrier Sense statistics register on page 778 to be
read from an incorrect page.  Also error out if the page select operation
fails.

Signed-off-by: Bruce Allan <bruce.w.allan@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>