b44: Set PHY address to NO_PHY if reset fails.

Do a PHY reset to test if there is an active phy and set the PHY address
to B44_PHY_ADDR_NO_PHY in case of an not active phy. This is needed for
the Linksys WRTSL54GS and Asus WL-500W.
This patch was used in OpenWRT for a long time.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Signed-off-by: David S. Miller <davem@davemloft.net>