LU-6174 osd-ldiskfs: perform proper division

LU-6174 osd-ldiskfs: perform proper division

The used value calculated for osd_inode_iteration() and
sf_items_updated_prior are both 64 bit values. The code
wrongly using do_div() which could truncate sf_items_updated_prior
to a 32 bit value. Use div64_u64() instead.

Change-Id: I3d76e399e6cf50460d98b1174de83263d9c2d3cc
Signed-off-by: James Simmons <jsimmons@infradead.org>
Reviewed-on: https://review.whamcloud.com/36750
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Wang Shilong <wshilong@ddn.com>
Reviewed-by: Shaun Tancheff <shaun.tancheff@hpe.com>