bootstd: Add a little more logging of bootflows

Add some logging to aid debugging of problems with bootflows.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/boot/bootdev-uclass.c b/boot/bootdev-uclass.c
index 522ecf3..99ee08e 100644
--- a/boot/bootdev-uclass.c
+++ b/boot/bootdev-uclass.c
@@ -546,6 +546,7 @@
 {
 	const struct bootdev_ops *ops = bootdev_get_ops(dev);
 
+	log_debug("->get_bootflow %s=%p\n", dev->name, ops->get_bootflow);
 	bootflow_init(bflow, dev, iter->method);
 	if (!ops->get_bootflow)
 		return default_get_bootflow(dev, iter, bflow);