dt-bindings: arm: amlogic: Move 'amlogic, meson-gx-ao-secure' binding to its own file

It is best practice to have 1 binding per file, so board level bindings
should be separate for various misc SoC bindings.

Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Carlo Caione <carlo@caione.org>
Cc: Kevin Hilman <khilman@baylibre.com>
Cc: devicetree@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-amlogic@lists.infradead.org
Signed-off-by: NRob Herring <robh@kernel.org>
Acked-by: NNeil Armstrong <narmstrong@baylibre.com>
Acked-by: NKevin Hilman <khilman@baylibre.com>
Signed-off-by: NKevin Hilman <khilman@baylibre.com>

Documentation/devicetree/bindings/arm/amlogic.txt

@@ -111,32 +111,3 @@ Board compatible values (alphabetically, grouped by SoC):
   - "amlogic,u200" (Meson g12a s905d2)
   - "amediatech,x96-max" (Meson g12a s905x2)
   - "seirobotics,sei510" (Meson g12a s905x2)
-
-Amlogic Meson Firmware registers Interface
-------------------------------------------
-
-The Meson SoCs have a register bank with status and data shared with the
-secure firmware.
-
-Required properties:
- - compatible: For Meson GX SoCs, must be "amlogic,meson-gx-ao-secure", "syscon"
-
-Properties should indentify components of this register interface :
-
-Meson GX SoC Information
-------------------------
-A firmware register encodes the SoC type, package and revision information on
-the Meson GX SoCs.
-If present, the following property should be added :
-
-Optional properties:
-  - amlogic,has-chip-id: If present, the interface gives the current SoC version.
-
-Example
--------
-
-ao-secure@140 {
-	compatible = "amlogic,meson-gx-ao-secure", "syscon";
-	reg = <0x0 0x140 0x0 0x140>;
-	amlogic,has-chip-id;
-};

Documentation/devicetree/bindings/arm/amlogic/amlogic,meson-gx-ao-secure.txt

+Amlogic Meson Firmware registers Interface
+------------------------------------------
+
+The Meson SoCs have a register bank with status and data shared with the
+secure firmware.
+
+Required properties:
+ - compatible: For Meson GX SoCs, must be "amlogic,meson-gx-ao-secure", "syscon"
+
+Properties should indentify components of this register interface :
+
+Meson GX SoC Information
+------------------------
+A firmware register encodes the SoC type, package and revision information on
+the Meson GX SoCs.
+If present, the following property should be added :
+
+Optional properties:
+  - amlogic,has-chip-id: If present, the interface gives the current SoC version.
+
+Example
+-------
+
+ao-secure@140 {
+	compatible = "amlogic,meson-gx-ao-secure", "syscon";
+	reg = <0x0 0x140 0x0 0x140>;
+	amlogic,has-chip-id;
+};