test(ff-a): bind and unbind notifications

Added tests to FFA_NOTIFICATION_BIND and FFA_NOTIFICATION_UNBIND calls:
- Cactus is requested to perform bind and unbind operations, using
test commands from previous commits.
- Use both calls in TFTF, to test use from VMs.

Signed-off-by: J-Alves <joao.alves@arm.com>
Change-Id: I970882a8f5de960e661f1c7fba01fc4870d8c40f
3 files changed