image: Rename load_addr, save_addr, save_size

These global variables are quite short and generic. In fact the same name
is more often used locally for struct members and function arguments.

Add a image_ prefix to make them easier to distinguish.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/cmd/reiser.c b/cmd/reiser.c
index 7f51b92..598fab4 100644
--- a/cmd/reiser.c
+++ b/cmd/reiser.c
@@ -154,7 +154,7 @@
 	}
 
 	/* Loading ok, update default load address */
-	load_addr = addr;
+	image_load_addr = addr;
 
 	printf ("\n%ld bytes read\n", filelen);
 	env_set_hex("filesize", filelen);