LU-11071 osd-ldiskfs: support bio integrity with Ubuntu 18

The recent landed for bio integrity broke building osd-ldisk for
both Ubuntu 18 and RHEL alt kernels. The reason is struct bio no
longer contains a struct block_devices. Instead we can get the
block device from the osd_device instead.

Change-Id: Ic72db4b29f7d0d1921fd97cb5df5c6c77908c92d
Signed-off-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-on: https://review.whamcloud.com/33624
Reviewed-by: Li Dongyang <dongyangli@ddn.com>
Reviewed-by: Li Xi <lixi@ddn.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>