LU-4993 osd-ldiskfs: Support 3.14 kernel changes to bio api

LU-4993 osd-ldiskfs: Support 3.14 kernel changes to bio api

In the 3.14 kernel code base several data fields in
struct bio were moved into a new structure called
bvec_iter. This patch updates osd-ldiskfs to handle
this api change.

Change-Id: I849a1d62462c58a79766c176060b27c621627646
Signed-off-by: James Simmons <uja.ornl@gmail.com>
Reviewed-on: http://review.whamcloud.com/10995
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>