bootstd: Add private bootmeth data to the bootflow

Some bootmeths need to store their own information related to the
bootflow, in addition to the generic information in struct bootflow.
Add a pointer for this.

Signed-off-by: Simon Glass <sjg@chromium.org>

boot/bootflow.c

@@ -432,6 +432,7 @@ void bootflow_free(struct bootflow *bflow)
 	free(bflow->buf);
 	free(bflow->os_name);
 	free(bflow->fdt_fname);
+	free(bflow->bootmeth_priv);
 }
 
 void bootflow_remove(struct bootflow *bflow)

include/bootflow.h

@@ -83,6 +83,7 @@ enum bootflow_flags_t {
  * @flags: Flags for the bootflow (see enum bootflow_flags_t)
  * @cmdline: OS command line, or NULL if not known (allocated)
  * @x86_setup: Pointer to x86 setup block inside @buf, NULL if not present
+ * @bootmeth_priv: Private data for the bootmeth
  */
 struct bootflow {
 	struct list_head bm_node;
@@ -108,6 +109,7 @@ struct bootflow {
 	int flags;
 	char *cmdline;
 	char *x86_setup;
+	void *bootmeth_priv;
 };
 
 /**