Allow the NFSv4 server to reply NFSERR_WRONGSEC for the SetClientID operation.

It was reported via email that a Linux client couldn't do a Kerberized
NFS mount when only "sec=krb5" was specified for the exports. The Linux
client attempted a mount via krb5i and the server replied NFSERR_SERVERFAULT.
Although NFSERR_WRONGSEC isn't listed as an error for SetClientID, I
think it is the correct reply, so this patch enables that.
I do not know if this fixes the mount attempt, but adding "krb5i" to the
list of allowed security flavours does allow the mount to work.

Reported by: joef@spectralogic.com
MFC after: 2 weeks