nfsd4: really fix nfs4err_resource in 4.1 case

nfsd4: really fix nfs4err_resource in 4.1 case

encode_getattr, for example, can return nfserr_resource to indicate it
ran out of buffer space.  That's not a legal error in the 4.1 case.
And in the 4.1 case, if we ran out of buffer space, we should have
exceeded a session limit too.

(Note in 3c7aa74c1426d92776a38a74658789a90818f319 "nfsd4: fix
nfs4err_resource in 4.1 case" we originally tried fixing this error
return before fixing the problem that we could error out while we still
had lots of available space.  The result was to trade one illegal error
for another in those cases.  We decided that was helpful, so reverted
the change in 34f33ab6d5877b5b39da30a56c42fbea36ff190e, and are only
reinstating it now that we've elimited almost all of those cases.)

Signed-off-by: J. Bruce Fields <bfields@redhat.com>