EX-6261 ptlrpc: extend sec bulk functionality

EX-6261 ptlrpc: extend sec bulk functionality

Client Side Data Compression(CSDC) needs buffers pool for efficient
work. Encryption used ptlrpc sec bulk, but it works with pages.

This patch extends sec bulk functionality to allocate different
size buffers. Memory shrinking and other usefull features
should still work as expected.

Signed-off-by: Artem Blagodarenko <ablagodarenko@ddn.com>
Change-Id: I929b4dfdcb0e8197f3804629b000af0d4bd6f2a0
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/50616
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>