RISC-V: KVM: Fix SBI implementation version

The SBI implementation version returned by KVM RISC-V should be the
Host Linux version code.

Fixes: c62a7685 ("RISC-V: KVM: Add SBI v0.2 base extension")
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <anup@brainfault.org>