sc->mii_anegticks according to whether the respective BGE chip
supports Fast Ethernet only or also Gigabit Ethernet.
- At least the BGE chips I've tested with wedge when isolating them
so document this as the reason for setting MIIF_NOISOLATE and
remove the unused (and partially even #ifdef'ed out) isolation
related code. Add code that panics if we encounter a non-zero MII
instance as generally there's no way a PHY requiring MIIF_NOISOLATE
can be handled gracefully in a multi-PHY configuration (it's ok for
the internal PHY of single-PHY-only-NIC to not support isolation
though).
- Additionally set MIIF_NOLOOP as loopback doesn't seem to work
either and remove the #ifdef'ed out code for adding respective
media. The MIIF_NOLOOP flag currently triggers nothing but
hopefully will be respected by mii_phy_setmedia() later on.
Reviewed by: jkim, yongari
MFC after: 1 month