py: gen-py-controls: Use Control class

Replace manual extraction of data from YAML with the Control helper
class. This centralizes YAML parsing and avoids manual mistakes.

In order to import the controls module, add the utils/codegen/ directory
to the PYTHONPATH through the Python build environment.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>

utils/codegen/meson.build

@@ -5,6 +5,7 @@
 py_build_env = environment()
 # \todo Investigate usage of PYTHONPYCACHEPREFIX for Python >= 3.8
 py_build_env.set('PYTHONDONTWRITEBYTECODE', '1')
+py_build_env.prepend('PYTHONPATH', meson.current_source_dir())
 
 py_modules += ['jinja2', 'yaml']