nfsd4: don't allow owner override on 4.1 CLAIM_FH opens

commit 9f415eb25574db4b73a9a712a4438e41dc284922 upstream.

The Linux client is using CLAIM_FH to implement regular opens, not just
recovery cases, so it depends on the server to check permissions
correctly.

Therefore the owner override, which may make sense in the delegation
recovery case, isn't right in the CLAIM_FH case.

Symptoms: on a client with 49f9a0fafd844c32f2abada047c0b9a5ba0d6255
"NFSv4.1: Enable open-by-filehandle", Bryan noticed this:

	touch test.txt
	chmod 000 test.txt
	echo test > test.txt

succeeding.

Reported-by: Bryan Schumaker <bjschuma@netapp.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>