net: dsa: felix: Configure Time-Aware Scheduler via taprio offload

Ocelot VSC9959 switch supports time-based egress shaping in hardware
according to IEEE 802.1Qbv. This patch add support for TAS configuration
on egress port of VSC9959 switch.

Felix driver is an instance of Ocelot family, with a DSA front-end. The
patch uses tc taprio hardware offload to setup TAS set function on felix
driver.

Signed-off-by: Xiaoliang Yang <xiaoliang.yang_1@nxp.com>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>