- Copy stable/10 (r259064) to releng/10.0 as part of the
10.0-RELEASE cycle.
- Update __FreeBSD_version [1]
- Set branch name to -RC1

[1] 10.0-CURRENT __FreeBSD_version value ended at '55', so
start releng/10.0 at '100' so the branch is started with
a value ending in zero.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

o) Allow devices to override the MDIO read and write functions presented to
the miibus attached to octe interfaces.
o) Add an SMI/MDIO interface to the MV88E61XX and use it for the switch PHY on
the Lanner MR-320. An actual driver for the switch PHY will come later.
Note that for now it intercepts and fakes MII_BMSR reads to prevent the
miibus from talking to anything but the switch itself.