hw/riscv/riscv-iommu: fix riscv_iommu_validate_process_ctx() check

hw/riscv/riscv-iommu: fix riscv_iommu_validate_process_ctx() check

'mode' will never be RISCV_IOMMU_CAP_SV32. We are erroring out in the
'switch' right before it if 'mode' isn't 0, 8, 9 or 10.

'mode' should be check with RISCV_IOMMU_DC_FSC_IOSATP_MODE_SV32.

Reported by Coverity via a "DEADCODE" ticket.

Resolves: Coverity CID 1564781
Fixes: 0c54acb8243 ("hw/riscv: add RISC-V IOMMU base emulation")
Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20241104123839.533442-3-dbarboza@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>