The ramdisk sections in doc/uImage.FIT/multi.its lack
load address and entry point properties. Using examples
from this file will result in unbootable image, u-boot
will issue the following error messages:

Can't get ramdisk subimage load address!
Ramdisk image is corrupt or invalid

This patch adds missing properties to ramdisk sections.

Signed-off-by: Felix Radensky <felix@embedded-sol.com>