Add support for configuring PSFP stream gates (IEEE 802.1Q-2018,
8.6.5.1.2).

Stream gates are time-based policers used by PSFP. Frames are dropped
based on the gate state (OPEN/ CLOSE), whose state will be altered based
on the Gate Control List (GCL) and current PTP time. Apart from
time-based policing, stream gates can alter egress queue selection for
the frames that pass through the Gate. This is done through Internal
Priority Selector (IPS). Stream gates are mapped from stream filters.
Signed-off-by: Daniel Machon <daniel.machon@microchip.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: David S. Miller <davem@davemloft.net>