ethtool: strset: fix message length calculation
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 v5.12.13 by commit cfc7f0e70d649e6d2233fba0d9390b525677d971, it was introduced in version v5.6 by commit 71921690f9745fef60a2bad425f30adf8cdc9da0. For more details please see the references link.