target/riscv: Check SUM in the correct register

target/riscv: Check SUM in the correct register

Table 9.5 "Effect of MPRV..." specifies that MPV=1 uses VS-level
vsstatus.SUM instead of HS-level sstatus.SUM.

For HLV/HSV instructions, the HS-level register does not apply, but
the VS-level register presumably does, though this is not mentioned
explicitly in the manual.  However, it matches the behavior for MPV.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Weiwei Li <liweiwei@iscas.ac.cn>
Tested-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Message-Id: <20230325105429.1142530-18-richard.henderson@linaro.org>
Message-Id: <20230412114333.118895-18-richard.henderson@linaro.org>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>