test(notifications): retrieve interrupt IDs

FFA_FEATURES can be used to query about certain features, namely to
retrieve interrupt ID of:
- Notification Pending Interrupt.
- Scheduler Receiver Interrupt.
- Managed Exit Interrupt.
As those are all needed in the scope of the notifications feature,
added test to validate they can be retrieved and have expected values.

Signed-off-by: J-Alves <joao.alves@arm.com>
Change-Id: I808170780118cff0dc89008e135897af7009ab37
4 files changed