refactor(notifications): tidy global notifications to SP tests

Tests that validate signaling of notifications to an SP, both from
another SP or from a VM had a similar body. Hence, defining a base
function to be used in both tests.

Change-Id: Id6b41d537a119bdeecd0e8e32d0ef720c17568af
Signed-off-by: J-Alves <joao.alves@arm.com>
1 file changed