Qualcomm Technologies, Inc. mdss-spi-display

mdss-spi-display is a spi interface display which support send frame
data and command to panel, compatible with SPI interface specification.

Required properties:
- compatible:		Must be "qcom,mdss-spi-display"
- qcom,mdss-fb-map:	pHandle that specifies the framebuffer to which the
			interface is mapped.

Optional properties:
- label:		A string used to describe the controller used.

Example:
mdss_spi_display: qcom,mdss_spi_display {
	compatible = "qcom,mdss-spi-display";
	label = "mdss spi display";

	mdss_fb0: qcom,mdss_fb_primary {
		cell-index = <0>;
		compatible = "qcom,mdss-fb";
	};
};