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
diff --git a/include/runtime_services/spm_common.h b/include/runtime_services/spm_common.h
index 91a3b8c..58569d5 100644
--- a/include/runtime_services/spm_common.h
+++ b/include/runtime_services/spm_common.h
@@ -25,6 +25,9 @@
 /* INTID for the managed exit virtual interrupt. */
 #define MANAGED_EXIT_INTERRUPT_ID	U(4)
 
+/* INTID for the notification pending interrupt. */
+#define NOTIFICATION_PENDING_INTERRUPT_INTID 5
+
 /** IRQ/FIQ pin used for signaling a virtual interrupt. */
 enum interrupt_pin {
 	INTERRUPT_TYPE_IRQ,