net: stmmac: add TSO check for header length

net: stmmac: add TSO check for header length

According to the STM32MP151 documentation which covers dwmac v4.2, the
hardware TSO feature can handle header lengths up to a maximum of 1023
bytes.

Add a .ndo_features_check() method implementation to check the header
length meets these requirements, otherwise fall back to software GSO.

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Link: https://patch.msgid.link/E1w7ptO-0000000EatC-39il@rmk-PC.armlinux.org.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>