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 a708352718c76819237accf2e9c72c47dab0bce0 "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 a2f00a6590200c65db81b14a3661f28a6f42bf5e, and are only
reinstating it now that we've elimited almost all of those cases.)

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