LU-9040 scrub: handle group boundary properly

LU-9040 scrub: handle group boundary properly

If the last bit in current inode bitmap is set, then the
osd_iit_param::offset will be set as the inode count of
per group (LDISKFS_INODES_PER_GROUP). Unfortunately, the
orignal logic for osd_inode_iteration() did not handle such
boundary value properly, as to the iteration will scan current
group again and again.

Signed-off-by: Fan Yong <fan.yong@intel.com>
Change-Id: Ie555838cd782a9378c6305485dd737b6bc6b2d46
Reviewed-on: https://review.whamcloud.com/25105
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>