common/populate: decrease the step of rm file

Now that we have allocated 2*4096*64/16(32768) inodes after "Inode btree",
 but the step of rm file is too large to create enough free inodes in agi.
 So the freecount is not enough large to make free_level gt 1 and call
 _scratch__populate on xfs will report the following failure(such as xfs/083):

Failed to create fino of sufficient height!

By decreasing the step of rm file, xfs/083 will pass.

Signed-off-by: Yang Xu <xuyang2018.jy@cn.fujitsu.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>

common/populate

@@ -271,7 +271,7 @@ _scratch_xfs_populate() {
 		touch "${dir}/${f}"
 	done
 
-	seq 0 "$((ino_per_rec + 1))" "${nr}" | while read f; do
+	seq 0 2 "${nr}" | while read f; do
 		rm -f "${dir}/${f}"
 	done