xfs_scrub: fix fractional reporting of single inodes

xfs_scrub: fix fractional reporting of single inodes

When there are fewer than 1024 inodes in the filesystem, scrub reports
fractional inodes in its final report:

35.2MiB data used;  5.0 inodes used.
34.2MiB data found; 5.0 inodes found.
5.0 inodes counted; 5.0 inodes checked.

Inodes are indivisible, so only report the fractional part when we have
a large enough number of inodes to perform a unit conversion:

35.2MiB data used;  5 inodes used.
34.2MiB data found; 5 inodes found.
5 inodes counted; 5 inodes checked.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>