spl: nand: Fix NULL-pointer dereference

spl_nand_fit_read unconditionally accesses load->priv. Ensure it is set.

Fixes: 00e180cc513 ("spl: nand: support loading i.MX container format file")
Signed-off-by: Sean Anderson <seanga2@gmail.com>
diff --git a/common/spl/spl_nand.c b/common/spl/spl_nand.c
index 07916be..5b6932b 100644
--- a/common/spl/spl_nand.c
+++ b/common/spl/spl_nand.c
@@ -105,7 +105,7 @@
 		struct spl_load_info load;
 
 		load.dev = NULL;
-		load.priv = NULL;
+		load.priv = &offset;
 		load.filename = NULL;
 		load.bl_len = bl_len;
 		load.read = spl_nand_fit_read;