LU-12477 ldiskfs: finish removing HAVE_CLEAR_RDONLY_ON_PUT

LU-12477 ldiskfs: finish removing HAVE_CLEAR_RDONLY_ON_PUT

A recent patch removed almost all occurances of
HAVE_CLEAR_RDONLY_ON_PUT.  There is still one in
an ldiskfs patch, and it is the only reason for that
patch.

So remove the patch.

Test-Parameters: trivial
Fixes: 20553c985a51 ("LU-12477 kernel: remove dev_read_only handling")
Signed-off-by: Mr NeilBrown <neilb@suse.de>
Change-Id: I5faf01aecd665b49bd3a74f9d968994c8db53c1c
Reviewed-on: https://review.whamcloud.com/38438
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Yang Sheng <ys@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>