riscv: traps: add missing prototype
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 v5.15.64 by commit f8aafb25ec38cf6f43cadb4c09ad2e577f48f349, it was introduced in version v5.14 by commit 31da94c25aea835ceac00575a9fd206c5a833fed. For more details please see the references link.