ixgbe: fix X550 default set_phy_power method

Even though X550 may later clear this value for certain devices
set it initially to support copper.

Signed-off-by: Don Skidmore <donald.c.skidmore@intel.com>
Tested-by: Krishneil Singh <krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>