SUNRPC: remove machine_cred field from struct auth_cred

The cred is a machine_cred iff ->principal is set, so there is no
need for the extra flag.

There is one case which deserves some
explanation. nfs4_root_machine_cred() calls rpc_lookup_machine_cred()
with a NULL principal name which results in not getting a machine
credential, but getting a root credential instead.
This appears to be what is expected of the caller, and is
clearly the result provided by both auth_unix and auth_gss
which already ignore the flag.

Signed-off-by: NeilBrown <[email protected]>
Signed-off-by: Anna Schumaker <[email protected]>
diff --git a/net/sunrpc/auth_gss/auth_gss.c b/net/sunrpc/auth_gss/auth_gss.c
index 762b071..b218e15 100644
--- a/net/sunrpc/auth_gss/auth_gss.c
+++ b/net/sunrpc/auth_gss/auth_gss.c
@@ -1395,9 +1395,7 @@ gss_create_cred(struct rpc_auth *auth, struct auth_cred *acred, int flags, gfp_t
 	 */
 	cred->gc_base.cr_flags = 1UL << RPCAUTH_CRED_NEW;
 	cred->gc_service = gss_auth->service;
-	cred->gc_principal = NULL;
-	if (acred->machine_cred)
-		cred->gc_principal = acred->principal;
+	cred->gc_principal = acred->principal;
 	kref_get(&gss_auth->kref);
 	return &cred->gc_base;
 
@@ -1610,7 +1608,6 @@ static int gss_renew_cred(struct rpc_task *task)
 	struct auth_cred acred = {
 		.cred = oldcred->cr_cred,
 		.principal = gss_cred->gc_principal,
-		.machine_cred = (gss_cred->gc_principal != NULL ? 1 : 0),
 	};
 	struct rpc_cred *new;