lisa.tests: Set DummyTestBundle res_dir parameter
lisa.tests: Set DummyTestBundle res_dir parameter

When running:
python -m nose

The deserialization test of DummyTestBundle fails
because the res_dir parameter is set to None,
which is not supported by TestBundle class.
Set it to a dummy path to fix it.

Suggested-by: Dougals Raillard <abfae2e624d97486db989bedb2b1aa43740c5d0a@arm.com>

ARM-software/lisa,ARM-software/lisa,credp/lisa,ARM-software/lisa,credp/lisa,ARM-software/lisa,credp/lisa,credp/lisa