target/riscv/kvm: fix timebase-frequency when using KVM acceleration

target/riscv/kvm: fix timebase-frequency when using KVM acceleration

The timebase-frequency of guest OS should be the same with host
machine. The timebase-frequency value in DTS should be got from
hypervisor when using KVM acceleration.

Signed-off-by: Yong-Xuan Wang <yongxuan.wang@sifive.com>
Message-ID: <20240314061510.9800-1-yongxuan.wang@sifive.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>