LU-10994 clio: remove cpo_assume, cpo_unassume, cpo_fini

LU-10994 clio: remove cpo_assume, cpo_unassume, cpo_fini

Remove the cl_page methods cpo_assume, cpo_unassume, and
cpo_fini. These methods were only implemented by the vvp layer and so
they can be easily inlined into cl_page_assume() and
cl_page_unassume().

Lustre-change: https://review.whamcloud.com/47373
Lustre-commit: 9045894fe0f5033334a39a35a6332dab4498e21e

LU-6142 clio: make cp_ref in cl_page a refcount_t

As this is used as a refcount, it should be declared
as one.

Lustre-change: https://review.whamcloud.com/49072
Lustre-commit: e19804a3b7e793a11b1c8b5e0db9f6315f243b8c

Signed-off-by: Mr. NeilBrown <neilb@suse.de>
Reviewed-by: Arshad Hussain <arshad.hussain@aeoncomputing.com>
Reviewed-by: Jian Yu <yujian@whamcloud.com>
Change-Id: I260c5593983bac6742cf7577c26a4903e95ceb7c
Signed-off-by: John L. Hammond <jhammond@whamcloud.com>
Reviewed-by: Patrick Farrell <pfarrell@whamcloud.com>
Reviewed-by: Bobi Jam <bobijam@hotmail.com>
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/54037
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>