iscsi-target: remove unnecessary check in iscsit_setup_np error path

Found by coverity.  At this point sock is non-NULL, so the check
to unnecessary.

Signed-off-by: Joern Engel <joern@logfs.org>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
diff --git a/drivers/target/iscsi/iscsi_target_login.c b/drivers/target/iscsi/iscsi_target_login.c
index 02d5ccd..480f2e0 100644
--- a/drivers/target/iscsi/iscsi_target_login.c
+++ b/drivers/target/iscsi/iscsi_target_login.c
@@ -978,8 +978,7 @@
 	return 0;
 fail:
 	np->np_socket = NULL;
-	if (sock)
-		sock_release(sock);
+	sock_release(sock);
 	return ret;
 }