dt-bindings: arm: bcm: Convert BCM2835 firmware binding to YAML

Convert the Raspberry Pi BCM2835 firmware binding document to YAML.
Verified with dt_binding_check and dtbs_check.

Signed-off-by: Florian Fainelli <[email protected]>
Tested-by: Nicolas Saenz Julienne <[email protected]>
Signed-off-by: Maxime Ripard <[email protected]>
Link: https://lore.kernel.org/r/5bc0b9be8544b07300fccab4d4f26e5e5d8e62b2.1592210452.git-series.maxime@cerno.tech
Signed-off-by: Stephen Boyd <[email protected]>

Author: ffainelli

Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-firmware.txt

@@ -0,0 +1,35 @@
+# SPDX-License-Identifier: GPL-2.0
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/arm/bcm/raspberrypi,bcm2835-firmware.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Raspberry Pi VideoCore firmware driver
+
+maintainers:
+  - Eric Anholt <[email protected]>
+  - Stefan Wahren <[email protected]>
+
+properties:
+  compatible:
+    items:
+      - const: raspberrypi,bcm2835-firmware
+      - const: simple-bus
+
+  mboxes:
+    $ref: '/schemas/types.yaml#/definitions/phandle'
+    description: |
+      Phandle to the firmware device's Mailbox.
+      (See: ../mailbox/mailbox.txt for more information)
+
+required:
+  - compatible
+  - mboxes
+
+examples:
+  - |
+    firmware {
+        compatible = "raspberrypi,bcm2835-firmware", "simple-bus";
+        mboxes = <&mailbox>;
+    };
+...