sfc: fix TX channel offset when using legacy interrupts
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 v5.10.146 by commit b4afd3878f961d3517f27b3213730fceef77945c, it was introduced in version v5.10.122 by commit bf2af9b24313553f3f0b30443220ab0ac8595d2d. For more details please see the references link.