Hello biothundernxt,
It does seem strange how the file system has extracted and is recognized whereas the image and dtb in boot/ are not. It would appear the images were not transferred since boot/ is empty. Please make sure to copy them using a Linux machine (acting as root) to the boot/ directory, e.g.:
$ sudo cp /home/user/kernel/4.4.8/arch/arm64/boot/Image boot/
$ sudo cp /home/user/kernel/4.4.8/arch/arm64/boot/dts/marvell/armada-3720-community.dtb boot/
Make sure the files are saved to the SD card before unplugging it from your Linux machine.
Another potential issue is your U-Boot variables which look for the images in var/ directory instead of boot/. Please set them correctly:
Marvell>> setenv image_name boot/Image
Marvell>> setenv fdt_name boot/armada-3720-community.dtb
