VAR-SOM-AM43 USB OTG host

VAR-SOM-AM43 - USB OTG as host

From a SW perspective, the developer should do the following:

• Download a VAR-SOM-AM43 kernel out-of-tree.
• Update var-som-am43.dtsi, as follows:

$ gedit arch/arm/boot/dts/var-som-am43.dtsi
...
    &usb1 {
            dr_mode = "host";
            //dr_mode = "otg"; 
            status = "okay";
            pinctrl-names = "default", "sleep";
            pinctrl-0 = <&usb1_pins_default>;
            pinctrl-1 = <&usb1_pins_sleep>;
    };

...

• Build var-som-am43.dtb and replace it on flash / NFS.

Once the var-som-am43.dtb has been replaced on the rootfs - The USB-OTG port will function in Host-only mode.

At this point, the user can simply connect a USB Mouse or DOK to the OTG port.