LU-11096 osd: wrap new blk integrity stuff

LU-11096 osd: wrap new blk integrity stuff

to be able to build Lustre against kernels with no blk integrity.

Change-Id: I050020e94524f4519fdf46a22f0d847979754291
Signed-off-by: Alex Zhuravlev <bzzz@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/32725
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Chris Horn <hornc@cray.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>