nfsd4: our filesystems are normally case sensitive

commit 2930d381 upstream.

Actually, xfs and jfs can optionally be case insensitive; we'll handle
that case in later patches.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>