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/common/spl/spl_net.c b/common/spl/spl_net.c
index 8033032..30c050c 100644
--- a/common/spl/spl_net.c
+++ b/common/spl/spl_net.c
@@ -19,14 +19,14 @@
 {
 	debug("%s: sector %lx, count %lx, buf %lx\n",
 	      __func__, sector, count, (ulong)buf);
-	memcpy(buf, (void *)(load_addr + sector), count);
+	memcpy(buf, (void *)(image_load_addr + sector), count);
 	return count;
 }
 
 static int spl_net_load_image(struct spl_image_info *spl_image,
 			      struct spl_boot_device *bootdev)
 {
-	struct image_header *header = (struct image_header *)load_addr;
+	struct image_header *header = (struct image_header *)image_load_addr;
 	int rv;
 
 	env_init();