drm/komeda: Enable dual-link support

drm/komeda: Enable dual-link support

Komeda HW can support dual-link which splits display frame to two halves
(left/link0, right/link1) and output them by two output links.
Due to the halved pixel rate of each link, the pxlclk of dual-link can be
reduced two times compare with single-link.

For enabling dual-link:
- The DT need to configure two output-links for the pipeline node.
- Komeda enable dual-link when both link0 and link1 have been connected.

Example of how the pipeline node will look like for dual-link setup

pipe0: pipeline@0 {
	clocks = <&fpgaosc2>;
	clock-names = "pxclk";
	reg = <0>;

	#address-cells = <1>;
	#size-cells = <0>;

	port@0 {
		reg = <0>;

		#address-cells = <1>;
		#size-cells = <0>;
		dp0_pipe0_link0: endpoint@0 {
			reg = <0>;
			remote-endpoint = <&dlink_connector_in0>;

		};
		dp0_pipe0_link1: endpoint@1 {
			reg = <1>;
			remote-endpoint = <&dlink_connector_in1>;
		};
	};
};

Signed-off-by: James Qian Wang (Arm Technology China) <james.qian.wang@arm.com>
Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190618081013.13638-3-james.qian.wang@arm.com