LU-12400 osd-ldiskfs: support multi-page bvec

LU-12400 osd-ldiskfs: support multi-page bvec

Mutli-page bvec support to enable bio_for_each_segment_all
needs users to supply bvec_iter_all as an iterator

Abstract the old (int) and new (bvec_iter_all) iterator types

Linux-commit: 6dc4f100c175dd0511ae8674786e7c9006cdfbfa

Test-Parameters: trivial
Cray-bug-id: LUS-7600
Signed-off-by: Shaun Tancheff <stancheff@cray.com>
Change-Id: I5a6decae9a4d470e268e20e86c29623b98e97205
Reviewed-on: https://review.whamcloud.com/35498
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>