* ARM AMBA Primecell PL011 serial UART

Required properties:
- compatible: must be "arm,primecell", "arm,pl011"
- reg: exactly one register range with length 0x1000
- interrupts: exactly one interrupt specifier

Optional properties:
- pinctrl:
	   When present, must have one state named "default",
	   and may contain a second name named "sleep". The former
	   state sets up pins for ordinary operation whereas
	   the latter state will put the associated pins to sleep
	   when the UART is unused
- clocks:
	   When present, the first clock listed must correspond to
	   the clock named UARTCLK on the IP block, i.e. the clock
	   to the external serial line, whereas the second clock
	   must correspond to the PCLK clocking the internal logic
	   of the block. Just listing one clock (the first one) is
	   deprecated.
- clocks-names:
	   When present, the first clock listed must be named
	   "uartclk" and the second clock listed must be named
	   "apb_pclk"
- dmas:	
	   When present, may have one or two dma channels.
	   The first one must be named "rx", the second one
	   must be named "tx".
- auto-poll:
	   Enables polling when using RX DMA.
- poll-rate-ms:
	   Rate at which poll occurs when auto-poll is set,
	   default 100ms.
- poll-timeout-ms:
	   Poll timeout when auto-poll is set, default
	   3000ms.

See also bindings/arm/primecell.txt

Example:

uart@80120000 {
	compatible = "arm,pl011", "arm,primecell";
	reg = <0x80120000 0x1000>;
	interrupts = <0 11 IRQ_TYPE_LEVEL_HIGH>;
	dmas = <&dma 13 0 0x2>, <&dma 13 0 0x0>;
	dma-names = "rx", "tx";
	clocks = <&foo_clk>, <&bar_clk>;
	clock-names = "uartclk", "apb_pclk";
};