riscv: s64ilp32: Disable KVM

Disable the KVM host feature for s64ilp32 first, and let's work on this
feature after the s64ilp32 main feature is merged.

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@kernel.org>
Cc: Anup Patel <anup@brainfault.org>