Add new file arm64/acpica/acpi_iort.c to support the "IO Remapping Table" (IORT). The table is specified in ARM document "ARM DEN 0049D" titled "IO Remapping Table Platform Design Document".
The IORT has information on the associations between PCI root complexes, SMMU blocks and GIC ITS blocks in the system.
The code added by the commit is to parse and save the information in the IORT table. It provides an API for the PCI controller to query the mapping of a specific child to a PIC XREF and a GIC device ID.
The acpi_iort.c has also code to check the GIC ITS nodes seen with MADT table for validity and with SRAT table to store the proximity information needed by ITS blocks.