io_uring: don't check req->file in io_fsync_prep()

io_uring: don't check req->file in io_fsync_prep()

BugLink: https://bugs.launchpad.net/bugs/1969107
commit ec858afda857e361182ceafc3d2ba2b164b8e889 upstream.

This is a leftover from the really old days where we weren't able to
track and error early if we need a file and it wasn't assigned. Kill
the check.

Cc: stable@vger.kernel.org # v5.15+
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 056e1e7c17136cea36267383a43d586509566931)
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>