Merge branch 'stmmac-ptp'

Giuseppe Cavallaro says:

====================
stmmac: fix PTP support

This subset of patches aim to fix the PTP support
for the stmmac and especially for 4.x chip series.
While setting PTP on an ST box with 4.00a Ethernet
core, the kernel panics due to a broken settings
of the descriptors. The patches review the
register configuration, the algo used for configuring
the protocol, the way to get the timestamp inside
the RX/TX descriptors and, in the end, the statistics
displayed by ethtool.

V2: RESEND all the patches adding the Acked-by.
====================

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