e1000e: commit speed/duplex changes for m88 PHY

Follow the convention used elsewhere in e1000e to 'commit' PHY changes
instead of directly writing to the PHY CTRL register to reset it.

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>