test(notifications): test schedule receiver interrupt

Refactor slightly tests that signal global notifications from SP to SP,
from VM to SP, and from SP to VM, to verify if SRI has been set
after the notifications set.
In this test the flag to delay sending SRI is being used, however no
validation interrupt sending has been delayed yet.

Signed-off-by: J-Alves <joao.alves@arm.com>
Change-Id: I28403bb1e09f2c2090eb9913d5b07b7eb245fb4d
2 files changed