Hi Rob,
i had the same problem. Looks like there are AP330 with different u-boot versions.
But luckily you can use the usb subsystem in u-boot to load the initramfs image.
If i remember correctly, you need a FAT16 formated usb drive with the initramfs + fdt image.
Connect the drive to the usb and do "usb start". You should see a usb tree including your drive.
You can do a "fatls" to list the files and with "fatload" you can load the image + fdt into the memory and boot the initramfs image with the bootm command.
It might be necessary to play with the right memory adresses, try the 2 mentioned in the commit (0x1000000 - 0x6000000)
Regards
Kirdes