target/riscv: Fix the bug of HLVX/HLV/HSV

target/riscv: Fix the bug of HLVX/HLV/HSV

We found that the hypervisor virtual-machine load and store instructions,
included HLVX/HLV/HSV, couldn't access guest userspace memory.

In the riscv-privileged spec, HLVX/HLV/HSV is defined as follow:
"As usual when V=1, two-stage address translation is applied, and
the HS-level sstatus.SUM is ignored."

But get_physical_address() doesn't ignore sstatus.SUM, when HLVX/HLV/HSV
accesses guest userspace memory. So this patch fixes it.

Signed-off-by: Yifei Jiang <jiangyifei@huawei.com>
Signed-off-by: Yipeng Yin <yinyipeng1@huawei.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 20201130012810.899-1-jiangyifei@huawei.com
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>