net: sfp: ensure TX_FAULT has deasserted before probing the PHY

TX_FAULT should be deasserted to indicate that the module has completed
its initialisation.  This may include the on-board PHY, so wait until
the module has deasserted TX_FAULT before probing the PHY.

This means that we need an extra state to handle a TX_FAULT that
remains set for longer than t_init, since using the existing handling
state would bypass the PHY probe.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>