util: Don't check if entries under /sys/fs/resctrl/(info/) are directories

util: Don't check if entries under /sys/fs/resctrl/(info/) are directories

We are skipping non-directories under /sys/fs/resctrl/(info/) since those are not
interesting for us.  However in tests it can sometimes happen that ent->d_type
is 0 instead of 4 (DT_DIR) for directories.

I've seen it fail on two machines.  Different machines, different systems, I
cannot reproduce it even using the same setup.  So one of the ways how to work
around this is call stat() on it.  The other one is not checking if it is a
directory since we'll find out eventually when we want to read some files
underneath it.

Signed-off-by: Martin Kletzander <mkletzan@redhat.com>