. Make internal service routines static.
. Use a consistent ordering of checks in MII_TICK. Do the work in the
mii_phy_tick() subroutine if appropriate.
. Call mii_phy_update() to trigger the callbacks.
We really want to be able to say "auto NWAY", "limited NWAY", and
"no NWAY". Unfortunately, this does not appear to be possible with
the current mediaopt structure.