device: support for mutable devices

Add support for mutable devices. Mutable devices are those which
can be modified after declaration, in-place, in kernel mode.

In order for a device to be mutable, the following must be true

  * `CONFIG_DEVICE_MUTABLE` must be y-selected
  * the Devicetree bindings for the device must include
    `mutable.yaml`
  * the Devicetree node must include the `zephyr,mutable` property

Signed-off-by: Christopher Friedt <cfriedt@meta.com>

dts/bindings/base/mutable.yaml

@@ -0,0 +1,13 @@
+# Copyright (c) 2023, Meta
+# SPDX-License-Identifier: Apache-2.0
+
+# Properties for Mutable devices
+
+properties:
+  zephyr,mutable:
+    type: boolean
+    description: |
+      True iff the device structure may be mutated.
+
+      Inherit this binding for devices that are runtime-modifiable, in-place.
+      This places the device structure into SRAM rather than Flash.