EX-8270 ptlrpc: make {get,put}_pages take order

EX-8270 ptlrpc: make {get,put}_pages take order

Pool index and pool order are now the same thing.  Let's
start by changing {get,put} pages, then we'll flow the
change in to the rest of the code.

Test-Parameters: trivial
Signed-off-by: Patrick Farrell <pfarrell@whamcloud.com>
Change-Id: I1ad789b9c848a8ef601b21271d32fe0c2bb929c8
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/52446
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>