* MSM Serial UARTDM

The MSM serial UARTDM hardware is designed for high-speed use cases where the
transmit and/or receive channels can be offloaded to a dma-engine. From a
software perspective it's mostly compatible with the MSM serial UART except
that it supports reading and writing multiple characters at a time.

Required properties:
- compatible: Should contain at least "qcom,msm-uartdm".
              A more specific property should be specified as follows depending
	      on the version:
		"qcom,msm-uartdm-v1.1"
		"qcom,msm-uartdm-v1.2"
		"qcom,msm-uartdm-v1.3"
		"qcom,msm-uartdm-v1.4"
- reg: Should contain UART register locations and lengths. The first
       register shall specify the main control registers. An optional second
       register location shall specify the GSBI control region.
       "qcom,msm-uartdm-v1.3" is the only compatible value that might
       need the GSBI control region.
- interrupts: Should contain UART interrupt.
- clocks: Should contain the core clock and the AHB clock.
- clock-names: Should be "core" for the core clock and "iface" for the
	       AHB clock.

Optional properties:
- dmas: Should contain dma specifiers for transmit and receive channels
- dma-names: Should contain "tx" for transmit and "rx" for receive channels

Examples:

A uartdm v1.4 device with dma capabilities.

serial@f991e000 {
	compatible = "qcom,msm-uartdm-v1.4", "qcom,msm-uartdm";
	reg = <0xf991e000 0x1000>;
	interrupts = <0 108 0x0>;
	clocks = <&blsp1_uart2_apps_cxc>, <&blsp1_ahb_cxc>;
	clock-names = "core", "iface";
	dmas = <&dma0 0>, <&dma0 1>;
	dma-names = "tx", "rx";
};

A uartdm v1.3 device without dma capabilities and part of a GSBI complex.

serial@19c40000 {
	compatible = "qcom,msm-uartdm-v1.3", "qcom,msm-uartdm";
	reg = <0x19c40000 0x1000>,
	      <0x19c00000 0x1000>;
	interrupts = <0 195 0x0>;
	clocks = <&gsbi5_uart_cxc>, <&gsbi5_ahb_cxc>;
	clock-names = "core", "iface";
};