iommu/riscv: Add ACPI support

iommu/riscv: Add ACPI support

RISC-V IO Mapping Table (RIMT) provides the information about the IOMMU
to the OS in ACPI. Add support for ACPI in RISC-V IOMMU drivers by using
RIMT data.

The changes at high level are,

a) Register the IOMMU with RIMT data structures.
b) Enable probing of platform IOMMU in ACPI way using the ACPIID defined
   for the RISC-V IOMMU in the BRS spec [1]. Configure the MSI domain if
   the platform IOMMU uses MSIs.

[1] - https://github.com/riscv-non-isa/riscv-brs/blob/main/acpi-id.adoc

Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20250818045807.763922-4-sunilvl@ventanamicro.com
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>