dt-bindings: riscv: Add Andes interrupt controller compatible string

Add "andestech,cpu-intc" compatible string to indicate that
Andes specific local interrupt is supported on the core,
e.g. AX45MP cores have 3 types of non-standard local interrupt
which can be handled in supervisor mode:

- Slave port ECC error interrupt
- Bus write transaction error interrupt
- Performance monitor overflow interrupt

These interrupts are enabled/disabled via a custom register
SLIE instead of the standard interrupt enable register SIE.

Signed-off-by: Yu Chien Peter Lin <peterlin@andestech.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Link: https://lore.kernel.org/r/20240222083946.3977135-5-peterlin@andestech.com


Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>