Failure to boot via UEFI

The Ubuntu preinstalled image provides GRUB as EFI/BOOT/BOOTRISCV64.EFI on the EFI system partition.

While U-Boot in [VisionFive2 Software v2.11.5](https://github.com/starfive-tech/VisionFive2/releases/tag/VF2_v2.11.5) is able to boot the SD-card [VisionFive2 Software v3.6.1](https://github.com/starfive-tech/VisionFive2/releases/tag/VF2_v3.6.1) fails to boot.