dts: bindings: add andestech,l2c

To descibe the AndesTech L2 cache. Besides, remove
redundant property in dtsi.

Signed-off-by: Wei-Tai Lee <wtlee@andestech.com>

dts/bindings/cache/andestech,l2c.yaml

@@ -0,0 +1,16 @@
+#
+# Copyright (c) 2024, Andes Technology Corporation.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+description:
+  This is a representation of AndesTech L2 cache node
+
+compatible: "andestech,l2c"
+
+include: base.yaml
+
+properties:
+  reg:
+    required: true

dts/riscv/andes/andes_v5_ae350.dtsi

@@ -205,7 +205,6 @@
 		l2_cache: cache-controller@e0500000 {
 			compatible = "andestech,l2c";
 			reg = <0xe0500000 0x1000>;
-			cache-unified;
 			status = "disabled";
 		};