bootstd: Support running bootdev hunters

Add a way to run a bootdev hunter to find bootdevs of a certain type. Add
this to the 'bootdev hunt' command. Test for this are added in a later
patch, since a useful test needs some hunters to work with.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/cmd/bootdev.c b/cmd/bootdev.c
index 80bfe28..28866fa 100644
--- a/cmd/bootdev.c
+++ b/cmd/bootdev.c
@@ -128,7 +128,12 @@
 	if (list) {
 		bootdev_list_hunters(priv);
 	} else {
-		/* TODO: implement hunting */
+		ret = bootdev_hunt(spec, true);
+		if (ret) {
+			printf("Failed (err=%dE)\n", ret);
+
+			return CMD_RET_FAILURE;
+		}
 	}
 
 	return 0;