SUNRPC: gss_alloc_msg - choose _either_ a v0 message or a v1 message

Add the missing 'break' to ensure that we don't corrupt a legacy 'v0' type
message by appending the 'v1'.

Cc: Bruce Fields <bfields@fieldses.org>
Cc: stable@vger.kernel.org
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

net/sunrpc/auth_gss/auth_gss.c

@@ -482,6 +482,7 @@ gss_alloc_msg(struct gss_auth *gss_auth,
 	switch (vers) {
 	case 0:
 		gss_encode_v0_msg(gss_msg);
+		break;
 	default:
 		gss_encode_v1_msg(gss_msg, service_name, gss_auth->target_name);
 	};