Mixel DSI DPHY for MX8

The MIPI-DSI DPHY IP block found on MX8 platforms comes along the MIPI-DSI
IP from Northwest Logic and represents the physical layer for the electrical
signals for DSI.

Required properties:
- compatible: 		"mixel,<soc>-mipi-dsi-phy"
- reg:			the register range of the PHY controller
- #phy-cells:		number of cells in PHY, as defined in
			Documentation/devicetree/bindings/phy/phy-bindings.txt
			this must be <0>

Optional properties:
- power-domains: 	phandle to power domain

Example:
	mipi0_phy: mipi0_phy@56228300 {
                compatible = "mixel,imx8qm-mipi-dsi-phy";
                reg = <0x0 0x56228300 0x0 0x100>;
                power-domains = <&pd_mipi0>;
                #phy-cells = <0>;
        };