target/riscv: Support MSTATUS.MPV/GVA only when RVH is enabled

target/riscv: Support MSTATUS.MPV/GVA only when RVH is enabled

MPV and GVA bits are added by hypervisor extension to mstatus
and mstatush (if MXLEN=32).

Signed-off-by: Weiwei Li <liweiwei@iscas.ac.cn>
Signed-off-by: Junqiang Wang <wangjunqiang@iscas.ac.cn>
Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20230603134236.15719-3-liweiwei@iscas.ac.cn>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>