GSD-2022-1006478 sfc/siena: fix null pointer dereference in efx_hard_start_xmit

sfc/siena: fix null pointer dereference in efxhardstartxmit This is an automated ID intended to aid in discovery of potential security vulnerabilities. The actual impact and attack plausibility have not yet been proven. This ID is fixed in Linux Kernel version v6.0 by commit...