bootstd: Update bootmeth_alloc_file() to record images

As a first step to recording images and where they came from, update
this function to do so, since it is used by two bootmeths

Create a helper function in the bootflow system, since recorded
images are always associated with bootflows.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/include/bootflow.h b/include/bootflow.h
index f407bb3..e09cff2 100644
--- a/include/bootflow.h
+++ b/include/bootflow.h
@@ -613,4 +613,19 @@
  * Return: Image name, or "unknown" if not known
  */
 const char *bootflow_img_type_name(enum bootflow_img_t type);
+
+/**
+ * bootflow_img_add() - Add a new image to a bootflow
+ *
+ * @bflow: Bootflow to add to
+ * @fname: Image filename (will be allocated)
+ * @type: Image type
+ * @addr: Address the image was loaded to, or 0 if not loaded
+ * @size: Image size
+ * Return: pointer to the added image, or NULL if out of memory
+ */
+struct bootflow_img *bootflow_img_add(struct bootflow *bflow, const char *fname,
+				      enum bootflow_img_t type, ulong addr,
+				      ulong size);
+
 #endif