EX-7433 osc: disable CPU-access features for RDMA only pages

EX-7433 osc: disable CPU-access features for RDMA only pages

Pages which cannot be accessed by the CPU are referred to
as RDMA only pages.  If pages cannot be accessed by the
CPU, it is impossible for us to do compression,
encryption, checksums, or short-io (data-in-RPC) on them.

This patch disables compression and encryption for these
pages and cleans up the code so checksums and short-io
are disabled by the same code.

The only user of RDMA only pages today is Nvidia's GPU
direct, so this patch disables compression and
encryption with GPU direct.

NB: We eventually intend to handle compression for
GPU direct with server side compress/decompress.

Signed-off-by: Patrick Farrell <pfarrell@whamcloud.com>
Change-Id: Iad9311617cddf27d3ff75a17429499c573067ea0
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/51770
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Sebastien Buisson <sbuisson@ddn.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>