ACPI: bus: Add acpi_riscv_init() function

Add a new function for RISC-V to do architecture specific initialization
similar to acpi_arm_init(). Some of the ACPI tables are architecture
specific and there is no reason trying to find them on other
architectures. So, add acpi_riscv_init() similar to acpi_arm_init().

Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
Tested-by: Björn Töpel <bjorn@rivosinc.com>
Link: https://patch.msgid.link/20240812005929.113499-4-sunilvl@ventanamicro.com


Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>