LU-7269 ptlrpc: remove ptlrpc_prep_req

LU-7269 ptlrpc: remove ptlrpc_prep_req

Remove unused functions ptlrpc_prep_req, ptlrpc_prep_req_pool
Combine __ptlrpc_request_bufs_pack and ptlrpc_request_bufs_pack

Signed-off-by: Ben Evans <bevans@cray.com>
Change-Id: I4e4e64aa1f7fa4c85daf311906f6417a513dcddc
Reviewed-on: http://review.whamcloud.com/16765
Tested-by: Jenkins
Reviewed-by: Frank Zago <fzago@cray.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Chris Horn <hornc@cray.com>