net: stmmac: move TSO VLAN tag insertion to core code

net: stmmac: move TSO VLAN tag insertion to core code

stmmac_tso_xmit() checks whether the skbuff is trying to offload
vlan tag insertion to hardware, which from the comment in the code
appears to be buggy when the TSO feature is used.

Rather than stmmac_tso_xmit() inserting the VLAN tag, handle this
in stmmac_features_check() which will then use core net code to
handle this. See net/core/dev.c::validate_xmit_skb()

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Link: https://patch.msgid.link/E1w7ptY-0000000EatO-42Qv@rmk-PC.armlinux.org.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>