Merge branch 'stmmac-swmac-desc-prefetch'

Mohammad Athari Bin Ismail says:

====================
Enable DWMAC HW descriptor prefetch

This patch series to add setting for HW descriptor prefetch for DWMAC
version 5.20 onwards. For Intel platform, enable the capability by
default.
====================

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