net: enetc: make sure all traffic classes can send large frames

net: enetc: make sure all traffic classes can send large frames

The enetc driver does not implement .ndo_change_mtu, instead it
configures the MAC register field PTC{Traffic Class}MSDUR[MAXSDU]
statically to a large value during probe time.

The driver used to configure only the max SDU for traffic class 0, and
that was fine while the driver could only use traffic class 0. But with
the introduction of mqprio, sending a large frame into any other TC than
0 is broken.

This patch fixes that by replicating per traffic class the static
configuration done in enetc_configure_port_mac().

Fixes: cbe9e835946f ("enetc: Enable TC offloading with mqprio")
Reported-by: Richie Pearn <richard.pearn@nxp.com>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: <Claudiu Manoil <claudiu.manoil@nxp.com>
Link: https://lore.kernel.org/r/20211020173340.1089992-1-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>