dt-bindings: Add Oxford Semiconductor Reset Controller bindings

Add bindings for the Oxford Semiconductor OXNAS reset controller.
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

Documentation/devicetree/bindings/reset/oxnas,reset.txt

+Oxford Semiconductor OXNAS SoC Family RESET Controller
+================================================
+
+Please also refer to reset.txt in this directory for common reset
+controller binding usage.
+
+Required properties:
+- compatible: Should be "oxsemi,ox810se-reset"
+- #reset-cells: 1, see below
+
+Parent node should have the following properties :
+- compatible: Should be "oxsemi,ox810se-sys-ctrl", "syscon", "simple-mfd"
+
+For OX810SE, the indices are :
+ - 0 : ARM
+ - 1 : COPRO
+ - 2 : Reserved
+ - 3 : Reserved
+ - 4 : USBHS
+ - 5 : USBHSPHY
+ - 6 : MAC
+ - 7 : PCI
+ - 8 : DMA
+ - 9 : DPE
+ - 10 : DDR
+ - 11 : SATA
+ - 12 : SATA_LINK
+ - 13 : SATA_PHY
+ - 14 : Reserved
+ - 15 : NAND
+ - 16 : GPIO
+ - 17 : UART1
+ - 18 : UART2
+ - 19 : MISC
+ - 20 : I2S
+ - 21 : AHB_MON
+ - 22 : UART3
+ - 23 : UART4
+ - 24 : SGDMA
+ - 25 : Reserved
+ - 26 : Reserved
+ - 27 : Reserved
+ - 28 : Reserved
+ - 29 : Reserved
+ - 30 : Reserved
+ - 31 : BUS
+
+example:
+
+sys: sys-ctrl@000000 {
+	compatible = "oxsemi,ox810se-sys-ctrl", "syscon", "simple-mfd";
+	reg = <0x000000 0x100000>;
+
+	reset: reset-controller {
+		compatible = "oxsemi,ox810se-reset";
+		#reset-cells = <1>;
+	};
+};