xfs_io: fix inode command with "-n" for bogus inode

xfs_io: fix inode command with "-n" for bogus inode

If we ask for the next allocated inode after a number for which
no other inode exists, the bulkstat returns success, but with
count == 0.  If we ignore this fact, we print a garbage result
from bstat.bs_ino in this case, so fix it.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>