dts: bindings: remove unused riscv,clint0

All platforms have been migrated to sifive,clint0 (or derivates).

Signed-off-by: Gerard Marull-Paretas <gerard.marull@nordicsemi.no>

dts/bindings/interrupt-controller/riscv,clint0.yaml

@@ -1,18 +0,0 @@
-# Copyright (c) 2020, Katsuhiro Suzuki.
-# SPDX-License-Identifier: Apache-2.0
-
-description: Common fields for the RISC-V Core-Local interruptor.
-
-include: [interrupt-controller.yaml, base.yaml]
-
-compatible: "riscv,clint0"
-
-properties:
-  reg:
-      required: true
-
-  "#interrupt-cells":
-      const: 1
-
-interrupt-cells:
-  - irq