Revert "nfs: take extra reference to fl->fl_file when running a LOCKU operation"

Revert "nfs: take extra reference to fl->fl_file when running a LOCKU operation"

This reverts commit 81bbc7ea5826f7798cd91c91de88e459af469083.

William reported that he was seeing instability with this patch, which
is likely due to the fact that it can cause the kernel to take a new
reference to a filp after the last reference has already been put.

Revert this patch for now, as we'll need to fix this in another way.

Cc: stable@vger.kernel.org
Reported-by: William Dauchy <william@gandi.net>
Signed-off-by: Jeff Layton <jeff.layton@primarydata.com>
Reviewed-by: "J. Bruce Fields" <bfields@fieldses.org>
Tested-by: "J. Bruce Fields" <bfields@fieldses.org>