LU-9859 libcfs: discard cfs_cap_t, use kernel_cap_t

LU-9859 libcfs: discard cfs_cap_t, use kernel_cap_t

lustre only sends 32bits of capabilities in on-the-wire RPC calls.
It current strips off higher bits and uses a 32bit cfs_cap_t
throughout.
Though there is a small memory cost, it is cleaner to use
kernel_cap_t throughout and only truncate when marshalling
data for RPC calls.

So this patch replaces cfs_cap_t with kernel_cap_t throughout,
and where a cfs_cap_t was previous stored in a __u32, we now
store cap.cap[0] instead.

With this, we can remove include/linux/libcfs/curproc.h

Linux-commit: 18f92a6e3d6bd00941ddfb5837835348f72d39dc

Lustre-change: https://review.whamcloud.com/43171
Lustre-commit: 0a6beb2a50f7a4f953a258b63c2ea1fbfd373092

Change-Id: If7dd7a16c218dfc0d520e189f021ed6bda3b93fd
Signed-off-by: Mr. NeilBrown <neilb@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/51743
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>