Motorola mc146818 compatible RTC
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Required properties:
  - compatible : "motorola,mc146818"
  - reg : should contain registers location and length.

Optional properties:
  - interrupts : should contain interrupt.
  - interrupt-parent : interrupt source phandle.
  - ctrl-reg : Contains the initial value of the control register also
    called "Register B".
  - freq-reg : Contains the initial value of the frequency register also
    called "Regsiter A".

"Register A" and "B" are usually initialized by the firmware (BIOS for
instance). If this is not done, it can be performed by the driver.

ISA Example:

	rtc@70 {
	         compatible = "motorola,mc146818";
	         interrupts = <8 3>;
	         interrupt-parent = <&ioapic1>;
	         ctrl-reg = <2>;
	         freq-reg = <0x26>;
	         reg = <1 0x70 2>;
	 };