NFSv4: Fix error handling in nfs4_sp4_select_mode()

Error code is set in the error handling cases but never used. Fix it.

Fixes: 937e3133cd0b ("NFSv4.1: Ensure we clear the SP4_MACH_CRED flags in nfs4_sp4_select_mode()")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

fs/nfs/nfs4proc.c

@@ -7793,7 +7793,7 @@ static int nfs4_sp4_select_mode(struct nfs_client *clp,
 	}
 out:
 	clp->cl_sp4_flags = flags;
-	return 0;
+	return ret;
 }
 
 struct nfs41_exchange_id_data {