iommu/riscv: Add IOTINVAL after updating DDT/PDT entries

In the Linux kernel, the following vulnerability has been resolved:

iommu/riscv: Add IOTINVAL after updating DDT/PDT entries

Add riscv_iommu_iodir_iotinval() to perform required TLB and context cache

invalidations after updating DDT or PDT entries, as mandated by the RISC-V

IOMMU specification (Section 6.3.1 and 6.3.2).