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/ximg.c b/cmd/ximg.c
index 22b2037..dccd114 100644
--- a/cmd/ximg.c
+++ b/cmd/ximg.c
@@ -33,7 +33,7 @@
 static int
 do_imgextract(cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
 {
-	ulong		addr = load_addr;
+	ulong		addr = image_load_addr;
 	ulong		dest = 0;
 	ulong		data, len;
 	int		verify;