dt-bindings: interrupt-controller: Add MIPS P8700 aclint-sswi

dt-bindings: interrupt-controller: Add MIPS P8700 aclint-sswi

Add ACLINT-SSWI variant for the MIPS P8700 SoC. This CPU has a SSWI device
compliant with the RISC-V draft spec (see [1]).

CPU indexes on this platform are not continuous, instead it uses bit-fields
to encode hart,core,cluster numbers, thus the DT property
"riscv,hart-indexes" is mandatory for it.

Signed-off-by: Vladimir Kondratiev <vladimir.kondratiev@mobileye.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/all/20250612143911.3224046-4-vladimir.kondratiev@mobileye.com
Link: https://github.com/riscvarchive/riscv-aclint