[PATCH -fixes] riscv: Fix ftrace syscall handling which are now prefixed with __riscv_

[Björn Töpel]

Alexandre Ghiti <alexghiti at rivosinc.com> writes:

> @Conor Dooley This fails checkpatch but the documentation here states
> that this is how to do:
> https://elixir.bootlin.com/linux/latest/source/Documentation/trace/ftrace-design.rst#L246

FWIW, I'll relax the PW CI checkpatch test going forward. It's way too
strict...