flashmap: Allocate at least one entry in kv_pair_new()

Change-Id: I971fa85ed977884d050790560a5a8f2ce955eb7c
Signed-off-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Reviewed-on: https://review.coreboot.org/14444
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

util/cbfstool/flashmap/kv_pair.c

@@ -56,7 +56,7 @@ struct kv_pair *kv_pair_new(void)
 {
 	struct kv_pair *kv;
 
-	kv = calloc(0, sizeof(*kv));
+	kv = calloc(1, sizeof(*kv));
 	if (!kv)
 		return NULL;