LU-4993 llite: 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 changed impacted the lustre loop device.
This patch brings support of these changes to the loop
device lustre uses.

Change-Id: I7cc9565bbf56e87e4465a76b7b5b959b063c3971
Signed-off-by: James Simmons <uja.ornl@gmail.com>
Reviewed-on: http://review.whamcloud.com/10337
Tested-by: Jenkins
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>