orangefs: do not check possibly stale size on truncate

commit 53950ef541675df48c219a8d665111a0e68dfc2f upstream.

Let the server figure this out because our size might be out of date or
not present.

The bug was that

	xfs_io -f -t -c "pread -v 0 100" /mnt/foo
	echo "Test" > /mnt/foo
	xfs_io -f -t -c "pread -v 0 100" /mnt/foo

fails because the second truncate did not happen if nothing had
requested the size after the write in echo.  Thus i_size was zero (not
present) and the orangefs_setattr though i_size was zero and there was
nothing to do.

Signed-off-by: Martin Brandenburg <martin@omnibond.com>
Signed-off-by: Mike Marshall <hubcap@omnibond.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>