hw/intc: Add RISC-V AIA APLIC device emulation

hw/intc: Add RISC-V AIA APLIC device emulation

The RISC-V AIA (Advanced Interrupt Architecture) defines a new
interrupt controller for wired interrupts called APLIC (Advanced
Platform Level Interrupt Controller). The APLIC is capabable of
forwarding wired interupts to RISC-V HARTs directly or as MSIs
(Message Signaled Interupts).

This patch adds device emulation for RISC-V AIA APLIC.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
Reviewed-by: Frank Chang <frank.chang@sifive.com>
Message-id: 20220204174700.534953-19-anup@brainfault.org
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>