Make the file path generation more transparent

Signed-off-by: Gabor Mezei <gabor.mezei@arm.com>
diff --git a/tf-psa-crypto/scripts/config.py b/tf-psa-crypto/scripts/config.py
index 8412637..474fea3 100755
--- a/tf-psa-crypto/scripts/config.py
+++ b/tf-psa-crypto/scripts/config.py
@@ -147,7 +147,7 @@
                     os.path.join(os.path.dirname(__file__),
                                  os.pardir,
                                  _path_in_tree),
-                    os.path.join(os.path.dirname(os.path.abspath(os.path.dirname(__file__))),
+                    os.path.join(os.path.dirname(os.path.dirname(os.path.abspath(__file__))),
                                  _path_in_tree)]
 
     def __init__(self, filename=None):