EX-8993 ofd: use niocount consistently

EX-8993 ofd: use niocount consistently

'niocount' refers to the number of remote niobufs, ie, the
number of separate IOs from the client.  Except for a few
places, where it's used to refer to the number of pages in
the entire RPC.  Eek.

Replace this usage with 'npages', making niocount usage
consistent.

Test-Parameters: trivial
Signed-off-by: Patrick Farrell <pfarrell@whamcloud.com>
Change-Id: I266087ad8dccadb54c054b0a11fb03dc9868a725
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/53206
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>