net: enetc: add hw tc hw offload features for PSPF capability

This patch is to let ethtool enable/disable the tc flower offload
features. Hardware ENETC has the feature of PSFP which is for per-stream
policing. When enable the tc hw offloading feature, driver would enable
the IEEE 802.1Qci feature. It is only set the register enable bit for
this feature not enable for any entry of per stream filtering and stream
gate or stream identify but get how much capabilities for each feature.

Signed-off-by: Po Liu <Po.Liu@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>