generate_*_tests.py: simplify test_suite_directory handling

test_suite_directory can be changed by a command line option in the
development branch but not in 2.28. Align the simplified version here with a
change in the development version
("generate_*_tests.py --directory: fix handling of relative path").

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/scripts/mbedtls_dev/test_data_generation.py b/scripts/mbedtls_dev/test_data_generation.py
index 2b90ef4..993cd4b 100644
--- a/scripts/mbedtls_dev/test_data_generation.py
+++ b/scripts/mbedtls_dev/test_data_generation.py
@@ -139,9 +139,8 @@
 
 class TestGenerator:
     """Generate test cases and write to data files."""
-    def __init__(self, options) -> None:
-        self.test_suite_directory = self.get_option(options, 'directory',
-                                                    'tests/suites')
+    def __init__(self, _options) -> None:
+        self.test_suite_directory = 'tests/suites'
         # Update `targets` with an entry for each child class of BaseTarget.
         # Each entry represents a file generated by the BaseTarget framework,
         # and enables generating the .data files using the CLI.
@@ -150,11 +149,6 @@
             for subclass in BaseTarget.__subclasses__()
         })
 
-    @staticmethod
-    def get_option(options, name: str, default: T) -> T:
-        value = getattr(options, name, None)
-        return default if value is None else value
-
     def filename_for(self, basename: str) -> str:
         """The location of the data file with the specified base name."""
         return posixpath.join(self.test_suite_directory, basename + '.data')