SUNRPC: Eliminate the RQ_AUTHERR flag

[ Upstream commit 9082e1d9 ]

Now that there is an alternate method for returning an auth_stat
value, replace the RQ_AUTHERR flag with use of that new method.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>