doc: Fix ramdisk examples in doc/uImage.FIT/multi.its

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: NFelix Radensky <felix@embedded-sol.com>

doc/uImage.FIT/multi.its

@@ -61,6 +61,8 @@
 			arch = "ppc";
 			os = "linux";
 			compression = "gzip";
+			load = <00000000>;
+			entry = <00000000>;
 			hash@1 {
 				algo = "sha1";
 			};
@@ -73,6 +75,8 @@
 			arch = "ppc";
 			os = "linux";
 			compression = "gzip";
+			load = <00000000>;
+			entry = <00000000>;
 			hash@1 {
 				algo = "crc32";
 			};