Realtek NPU present in RTS3915/RTS3916 IPCam Processor

Required properties:
- compatible: "realtek,rts3915-npu"
- memory-region: phandle to a node describing reserved memory (see
  Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt)
  to be used for the NPU; vipcore.ko must have it and it's optional for
  galcore.ko
- reg: Physical base address and length of the NPU's registers.
  Must contain two fields:
  - first field for NPU register base address
  - second field for NPU register range length
- interrupts-parent: The IRQ domain which the interrupts belongs to, must be:
  - "<&vecintc>".
- interrupts: IRQ offset in IRQ domain designated in interrupts-parent.
- clocks: Must contain an entry for each entry in clock-names.
  See ../clocks/clock-bindings.txt for details.
- clock-names: Must include the following entries:
  - nnbus_ck
  - nncore_ck
- clock-frequency: Overide the default NPU core clock frequency specified in
  clocks, must be one value of below:
  - 120000000
  - 400000000
  - 480000000
  - 500000000
- resets: Contain an entry of two fields for reset specifier.
  - first field for reset controller handler
  - second field for NPU reset control number
  See ../reset/reset.txt for details.
- reset-names: A string name for reset specifier entry designated in resets.

Example for rts_nn:

	rts_nn@0x18b00000 {
		compatible = "realtek,rts3915-npu";
		reg = <0x18b00000 0x100000>;
		memory-region = <&nn_reserved>;
		interrupt-parent = <&vecintc>;
		interrupts = <BSP_IRQ_NN>;
		clocks = <&clks RLX_CLK_NN_BUS>, \
			<&clks RLX_CLK_NNCORE_CK>;
		clock-names = "nnbus_ck", "nncore_ck";
		clock-frequency = <500000000>;
		resets = <&reset FORCE_RESET_NN>;
		reset-names = "nn_rst";
		status = "disabled";
	};
