ns2: Memory allocation failures are ENOMEM, not ENOSPC

ENOSPC is used with non-volatile (disk) storage, while ENOMEM is
customarily used for RAM allocation failures.

Change-Id: Ia4c16d8278dc30c7cc69169b18428cda5272738d
diff --git a/src/gb/gprs_ns2_frgre.c b/src/gb/gprs_ns2_frgre.c
index 863f8f2..88ef037 100644
--- a/src/gb/gprs_ns2_frgre.c
+++ b/src/gb/gprs_ns2_frgre.c
@@ -565,7 +565,7 @@
 	priv = bind->priv = talloc_zero(bind, struct priv_bind);
 	if (!priv) {
 		gprs_ns2_free_bind(bind);
-		return -ENOSPC;
+		return -ENOMEM;
 	}
 	priv->fd.cb = frgre_fd_cb;
 	priv->fd.data = bind;