RK3288 7.1双屏显示配置

3288最强功能之一就是双屏异显，7.1以上不需要打补丁，RK已经把补丁打好，只需要配置dts以及build.prop变量即可。

1.配置dts支持mipi+edp双屏显示：

首先是mipi的dts配置

&dsi0 {
    status = "okay";
    //rockchip,lane-rate = <400>;

    panel: panel {
        compatible = "simple-panel-dsi";
        reg = <0>;
        backlight = <&backlight>;
        //enable-gpios = <&gpio7 3 GPIO_ACTIVE_HIGH>;  //gpio7_a3 mark
        //reset-gpios = <&gpio7 4 GPIO_ACTIVE_LOW>;
        power-supply = <&vcc_lcd>;
        dsi,flags = <(MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_BURST | MIPI_DSI_MODE_LPM | MIPI_DSI_MODE_EOT_PACKET|MIPI_DSI_MODE_VIDEO_HBP)>;
        dsi,format = <MIPI_DSI_FMT_RGB888>;
        dsi,lanes = <4>;
        reset-delay-ms = <20>;
        init-delay-ms = <20>;
        enable-delay-ms = <120>;
 &nbs