dt-bindings: nvmem: add binding for Rockchip OTP controller

Newer Rockchip SoCs use a different IP for accessing special one-
time-programmable memory, so add a binding for these controllers.

Signed-off-by: Heiko Stuebner <[e-mail]>
Reviewed-by: Rob Herring <[e-mail]>
Signed-off-by: Srinivas Kandagatla <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

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

···
+Rockchip internal OTP (One Time Programmable) memory device tree bindings
+
+Required properties:
+- compatible: Should be one of the following.
+  - "rockchip,px30-otp" - for PX30 SoCs.
+  - "rockchip,rk3308-otp" - for RK3308 SoCs.
+- reg: Should contain the registers location and size
+- clocks: Must contain an entry for each entry in clock-names.
+- clock-names: Should be "otp", "apb_pclk" and "phy".
+- resets: Must contain an entry for each entry in reset-names.
+  See ../../reset/reset.txt for details.
+- reset-names: Should be "phy".
+
+See nvmem.txt for more information.
+
+Example:
+	otp: otp@ff290000 {
+		compatible = "rockchip,px30-otp";
+		reg = <0x0 0xff290000 0x0 0x4000>;
+		#address-cells = <1>;
+		#size-cells = <1>;
+		clocks = <&cru SCLK_OTP_USR>, <&cru PCLK_OTP_NS>,
+			 <&cru PCLK_OTP_PHY>;
+		clock-names = "otp", "apb_pclk", "phy";
+	};