rpc: fix gss_svc_init cleanup on failure

[ Upstream commit 5a4753446253a427c0ff1e433b9c4933e5af207c ]

The failure case here should be rare, but it's obviously wrong.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>