ACPICA: actbl2: Add definitions for RIMT

ACPICA commit 73c32bc89cad64ab19c1231a202361e917e6823c

RISC-V IO Mapping Table (RIMT) is a new static table defined for RISC-V
to communicate IOMMU information to the OS. The specification for RIMT
is available at [1]. Add structure definitions for RIMT.

Link: https://github.com/riscv-non-isa/riscv-acpi-rimt [1]
Link: https://github.com/acpica/acpica/commit/73c32bc8


Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://patch.msgid.link/10665648.nUPlyArG6x@rjwysocki.net