hw/riscv/riscv-iommu.c: fault when !PTE_U and no priv access

All IOMMU accesses are assumed to be user mode unless told otherwise, i.e. we have a process_id. In case we have a non-user mode leaf PTE (PTE_U isn't set) and we are running in user mode, we need to throw a fault. This also reflects on qos-riscv-iommu tests: the tests always run in user mode so our PTEs must have PTE_U (bit 0x10) set. Fixes: 0c54acb8243d ("hw/riscv: add RISC-V IOMMU base emulation") Resolves: https://gitlab.com/qemu-project/qemu/-/work_items/3553 Signed-off-by: Daniel Henrique Barboza <daniel.barboza@oss.qualcomm.com> Reviewed-by: Nutty Liu <nutty.liu@hotmail.com> Reviewed-by: Chao Liu <chao.liu.zevorn@gmail.com> Message-ID: <20260701121111.537654-3-daniel.barboza@oss.qualcomm.com> Signed-off-by: Alistair Francis <alistair.francis@wdc.com>