Add support for Gud USB Display

Gud (https://github.com/notro/gud) is a USB display driver that can be used with a raspberry pi to enable display output on a oneplus 6/6t (or any device with usb host mode) without needing display output built into the port.

The driver is already in the kernel as of 5.13

The kernel simply needs to be compiled with:

CONFIG_DRM_GUD=m

in the defconfig for it to be enabled.

Once OTG is functional on sdm845, this should enable usb displays out of the box.