Merge tag 'u-boot-amlogic-20200420' of https://gitlab.denx.de/u-boot/custodians/u-boot-amlogic

- enable DM_RNG on meson boards
- fix SMBIOS info on Odroid-C2
- Fix video output on GXBB/GXL/GXM boards
- add USB gadget support for GXL/GXM boards