phy: enable auto-negotiate with software reset

commit a058052c
net: phy: do not read configuration register on reset

broke atheros phy at8035 for the nitrogen6sx board
maybe others too.

This was supposed to be fixed by
commit 903d384d
Author: Alison Wang <b18965@freescale.com>
Date:   Fri Feb 19 15:52:28 2016 +0800

    net: phy: atheros: Fix problem with phy_reset() clearing BMCR
___
But still broken on Nitrogen6sx

Signed-off-by: Troy Kisky <troy.kisky@boundarydevices.com>