Merge branch 'PTP-support-for-DSA-and-mv88e6xxx-driver'

Andrew Lunn says:

====================
PTP support for DSA and mv88e6xxx driver.

This patchset adds support for using the PTP hardware in switches
supported by the mv88e6xxx driver. The code was produces in
collaboration with Brandon Streiff doing the initial implementation,
and then Richard Cochran and Andrew Lunn making further changes and
cleanups.

The code is sufficient to use ptp4l on a single DSA interface, either
as a master or a slave. Due to the use of an MDIO bus to access the
switch, reading hardware timestamps is slower than what ptp4l
expects. Thus it is necessary to use the option
--tx_timestamp_timeout=32. Heavy use of ethtool -S, or bridge fdb show
can also upset ptp4l. Patches to address this will follow.

Further work is requires to support bridges using Boundary Clock or
Transparent Clock mode.

Since the RFC, an overflow bug has been fixed. Brandon Streiff
has also Acked-by: the updates to his initial patchset.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>