ENGR00237452 i.MX6:IEEE1588: disable phy Ar8031 SmartEEE

ENGR00237452 i.MX6:IEEE1588: disable phy Ar8031 SmartEEE

Connecting two boards directly more than 2 hours, Ar8031 phy link
status generates glitch, which cause ethernet link down/up issue, but
ethernet still be active. There have three cases to validate the issue:

Item#1: If add performance stress test while runing IEEE1588, the link
	down/up issue cannot be found.
Item#2: If insert switch between two net nodes and run IEEE1588 test,
	the issue also cannot be found.
Item#3: If disable AR8031 SmartEEE feature, after two days overnight test,
	no such issue found.

The issue is caused by phy Ar8031 SmartEEE feature, Item#1 and Item#2 can
prevent phy enter lpm mode, which match the Item#3 test result, so disable
SmartEEE feature to avoid the link issue generation.

Signed-off-by: Fugang Duan  <B38611@freescale.com>