net: stmmac: Tx coe sw fallback

net: stmmac: Tx coe sw fallback

[ Upstream commit 8452a05b2c633b708dbe3e742f71b24bf21fe42d ]

Add sw fallback of tx checksum calculation for those tx queues that
don't support tx checksum offloading. DW xGMAC IP can be synthesized
such that it can support tx checksum offloading only for a few
initial tx queues. Also as Serge pointed out, for the DW QoS IP, tx
coe can be individually configured for each tx queue.

So when tx coe is enabled, for any tx queue that doesn't support
tx coe with 'coe-unsupported' flag set will have a sw fallback
happen in the driver for tx checksum calculation when any packets to
be transmitted on these tx queues.

Signed-off-by: Rohan G Thomas <rohan.g.thomas@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Stable-dep-of: c2945c435c99 ("net: stmmac: Prevent DSA tags from breaking COE")
Signed-off-by: Sasha Levin <sashal@kernel.org>