nvmem: dt: document lpc1850 OTP binding

Documenation for the LPC18xx/43xx OTP memory bindings.
Signed-off-by: Joachim Eastwood <manabian@gmail.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/nvmem/lpc1850-otp.txt

+* NXP LPC18xx OTP memory
+
+Internal OTP (One Time Programmable) memory for NXP LPC18xx/43xx devices.
+
+Required properties:
+  - compatible: Should be "nxp,lpc1850-otp"
+  - reg: Must contain an entry with the physical base address and length
+    for each entry in reg-names.
+  - address-cells: must be set to 1.
+  - size-cells: must be set to 1.
+
+See nvmem.txt for more information.
+
+Example:
+  otp: otp@40045000 {
+    compatible = "nxp,lpc1850-otp";
+    reg = <0x40045000 0x1000>;
+    #address-cells = <1>;
+    #size-cells = <1>;
+  };