dt-bindings: cache: bt1-l2-ctl: Remove unused bindings

As stated in [1] the Baikal platforms are not supported and
the respective driver code has just been removed. Remove
unused bindings.

Link: https://lore.kernel.org/lkml/22b92ddf-6321-41b5-8073-f9c7064d3432@infradead.org/ [1]
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://patch.msgid.link/20260225173930.3819351-3-andriy.shevchenko@linux.intel.com
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>

Documentation/devicetree/bindings/cache/baikal,bt1-l2-ctl.yaml

@@ -1,63 +0,0 @@
-# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
-# Copyright (C) 2020 BAIKAL ELECTRONICS, JSC
-%YAML 1.2
----
-$id: http://devicetree.org/schemas/cache/baikal,bt1-l2-ctl.yaml#
-$schema: http://devicetree.org/meta-schemas/core.yaml#
-
-title: Baikal-T1 L2-cache Control Block
-
-maintainers:
-  - Serge Semin <fancer.lancer@gmail.com>
-
-description: |
-  By means of the System Controller Baikal-T1 SoC exposes a few settings to
-  tune the MIPS P5600 CM2 L2 cache performance up. In particular it's possible
-  to change the Tag, Data and Way-select RAM access latencies. Baikal-T1
-  L2-cache controller block is responsible for the tuning. Its DT node is
-  supposed to be a child of the system controller.
-
-properties:
-  compatible:
-    const: baikal,bt1-l2-ctl
-
-  reg:
-    maxItems: 1
-
-  baikal,l2-ws-latency:
-    $ref: /schemas/types.yaml#/definitions/uint32
-    description: Cycles of latency for Way-select RAM accesses
-    default: 0
-    minimum: 0
-    maximum: 3
-
-  baikal,l2-tag-latency:
-    $ref: /schemas/types.yaml#/definitions/uint32
-    description: Cycles of latency for Tag RAM accesses
-    default: 0
-    minimum: 0
-    maximum: 3
-
-  baikal,l2-data-latency:
-    $ref: /schemas/types.yaml#/definitions/uint32
-    description: Cycles of latency for Data RAM accesses
-    default: 1
-    minimum: 0
-    maximum: 3
-
-additionalProperties: false
-
-required:
-  - compatible
-
-examples:
-  - |
-    l2@1f04d028 {
-      compatible = "baikal,bt1-l2-ctl";
-      reg = <0x1f04d028 0x004>;
-
-      baikal,l2-ws-latency = <1>;
-      baikal,l2-tag-latency = <1>;
-      baikal,l2-data-latency = <2>;
-    };
-...