config.py: Simplify crypto config default path setting

In 3.6, it can be only include/psa/crypto_config.h

Signed-off-by: Ronald Cron <ronald.cron@arm.com>
diff --git a/scripts/config.py b/scripts/config.py
index 957127e..47d74ce 100755
--- a/scripts/config.py
+++ b/scripts/config.py
@@ -286,11 +286,7 @@
     # Temporary, while Mbed TLS does not just rely on the TF-PSA-Crypto
     # build system to build its crypto library. When it does, the
     # condition can just be removed.
-    _path_in_tree = ('include/psa/crypto_config.h'
-                     if not os.path.isdir(os.path.join(os.path.dirname(__file__),
-                                                       os.pardir,
-                                                       'tf-psa-crypto')) else
-                     'tf-psa-crypto/include/psa/crypto_config.h')
+    _path_in_tree = 'include/psa/crypto_config.h'
     default_path = [_path_in_tree,
                     os.path.join(os.path.dirname(__file__),
                                  os.pardir,