bloblist: Support initing from multiple places

Typically the bloblist is set up after the devicetree is present. This
makes sense because bloblist may use malloc() to allocate the space it
needs.

However sometimes the devicetree itself may be present in the bloblist.
In that case it is at a known location in memory so we can init the
bloblist very early, before devicetree.

Add a flag to indicate whether the bloblist has been inited. Add a
function to init it only if needed. Use that in the init sequence.

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

include/bloblist.h

@@ -413,8 +413,26 @@ void bloblist_reloc(void *to, uint to_size, void *from, uint from_size);
  * standard passage. The size is detected automatically so CONFIG_BLOBLIST_SIZE
  * can be 0.
  *
+ * Sets GD_FLG_BLOBLIST_READY in global_data flags on success
+ *
  * Return: 0 if OK, -ve on error
  */
 int bloblist_init(void);
 
+#if CONFIG_IS_ENABLED(BLOBLIST)
+/**
+ * bloblist_maybe_init() - Init the bloblist system if not already done
+ *
+ * Calls bloblist_init() if the GD_FLG_BLOBLIST_READY flag is not et
+ *
+ * Return: 0 if OK, -ve on error
+ */
+int bloblist_maybe_init(void);
+#else
+static inline int bloblist_maybe_init(void)
+{
+	return 0;
+}
+#endif /* BLOBLIST */
+
 #endif /* __BLOBLIST_H */