spl: Create a function to init spl_load_info

Rather than having every caller set this up individually, create a
common init function. This allows new fields to be added without the
risk of them being left uninited.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Michael Trimarchi <michael@amarulasolutions.com>
diff --git a/common/spl/spl_net.c b/common/spl/spl_net.c
index be7278b..2be7b73 100644
--- a/common/spl/spl_net.c
+++ b/common/spl/spl_net.c
@@ -47,8 +47,7 @@
 		return rv;
 	}
 
-	spl_set_bl_len(&load, 1);
-	load.read = spl_net_load_read;
+	spl_load_init(&load, spl_net_load_read, NULL, 1);
 	return spl_load(spl_image, bootdev, &load, 0, 0);
 }
 #endif