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 <[email protected]>
Signed-off-by: Yipeng Yin <[email protected]>
Reviewed-by: Alistair Francis <[email protected]>
Message-id: 20201130012810[email protected]
Signed-off-by: Alistair Francis <[email protected]>