dt-bindings: interrupt-controller: Add SpacemiT K1 PLIC

Add compatible string for SpacemiT K1 PLIC.

Signed-off-by: Yangyu Chen <cyy@cyyself.name>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Acked-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Yixun Lan <dlan@gentoo.org>

Author: cyyself

Documentation/devicetree/bindings/interrupt-controller/sifive,plic-1.0.0.yaml

@@ -59,6 +59,7 @@ properties:
           - enum:
               - canaan,k210-plic
               - sifive,fu540-c000-plic
+              - spacemit,k1-plic
               - starfive,jh7100-plic
               - starfive,jh7110-plic
           - const: sifive,plic-1.0.0