net, phy: atheros ar803x bug

commit 626ee1e3 "phylib: update atheros ar803x phy"

leads in failing ethernet on the pxm2 board.

Calling genphy_config() instead of ar8021_config(),
which seems for ar8021 phys not ar803x phys, make
it working again.

Signed-off-by: Heiko Schocher <hs@denx.de>
Cc: Shengzhou Liu <Shengzhou.Liu@freescale.com>
Cc: Joe Hershberger <joe.hershberger@gmail.com>