e1000: add support for Marvell Alaska M88E1118R PHY

This patch adds support for Marvell Alask M88E188R PHY chips. Support for
other M88* PHYs is already there, so there is nothing more to add than its
PHY id.

CC: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Florian Fainelli <ffainelli@freebox.fr>
Acked-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>