overlay/038: test consistent values of st_ino/d_ino for subdirs

overlay/038: test consistent values of st_ino/d_ino for subdirs

This commit implements similar changes made to overlay/038 test i.e. in
addition to checking consistent values of st_ino/d_ino for "."  and ".."
entries, check also the values for subdir inside each tested directory
setup.

Signed-off-by: Chandan Rajendra <chandan@linux.vnet.ibm.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Eryu Guan <eguan@redhat.com>