bootstd: Add a way to set up a bootflow

Add a function to init a bootflow, to reduce code duplication.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/boot/bootflow.c b/boot/bootflow.c
index 5d94a27..f9ad409 100644
--- a/boot/bootflow.c
+++ b/boot/bootflow.c
@@ -339,6 +339,15 @@
 	} while (1);
 }
 
+void bootflow_init(struct bootflow *bflow, struct udevice *bootdev,
+		   struct udevice *meth)
+{
+	memset(bflow, '\0', sizeof(*bflow));
+	bflow->dev = bootdev;
+	bflow->method = meth;
+	bflow->state = BOOTFLOWST_BASE;
+}
+
 void bootflow_free(struct bootflow *bflow)
 {
 	free(bflow->name);