feat(amd): add test for register notifier EEMI API

Add a test case to validate the register notification handling
functionality of the EEMI API in the TF-A test framework. The test:

- Registers a notifier using `test_register_notifier()`.
- Waits for a notification within a predefined timeout.
- If received, unregisters the notifier using
  `test_unregister_notifier()`.

Change-Id: I4454ef8644851a2dedc0a224fa220062fed1d635
Signed-off-by: Madhav Bhatt <madhav.bhatt@amd.com>
6 files changed