kgdboc: fix return value of __setup handler
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 v4.14.276 by commit c7a24a174143ef91f763b5b4f7213bf8a16896a1, it was introduced in version v4.14.81 by commit 8305d98c58d238b82c0def1e4395724381c58c9e. For more details please see the references link.