generic: ar8216: fix PHY features setup

Sujith says:

This commit breaks the WAN port on my AP96 - DHCP fails.
Reverting it fixes the issue.

  commit b67cc3a0cdd02973610d4d5a63226d1c44841e94
  Author: juhosg <juhosg@3c298f89-4303-0410-b956-a3cf2f4a3e73>
  Date:   Fri Feb 8 09:13:18 2013 +0000

    generic: ar8216: simplify phy features setup

    Signed-off-by: Gabor Juhos <juhosg@openwrt.org>

    git-svn-id: svn://svn.openwrt.org/openwrt/trunk@355183c298f89-4303-0410-b956-a3cf2f4a3e73

This change restores the previous behaviour and moves
the code into the ar8216_probe function.

Reported-by: Sujith Manoharan <sujith@msujith.org>
Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Tested-by: Sujith Manoharan <sujith@msujith.org>

git-svn-id: svn://svn.openwrt.org/openwrt@35549 3c298f89-4303-0410-b956-a3cf2f4a3e73