refactor(interrupts): remove ffa_interrupts_get function

As part of the Secure Interrupts refactoring we want to introduce
consistency across the SPMC and Hypervisor implementation therefore
use api_interrupt_get.

Signed-off-by: Daniel Boulby <daniel.boulby@arm.com>
Change-Id: I6d7e67efada0eff141551e78eed8e3c33e655d88
diff --git a/src/arch/aarch64/hypervisor/handler.c b/src/arch/aarch64/hypervisor/handler.c
index 85bd6a0..852d397 100644
--- a/src/arch/aarch64/hypervisor/handler.c
+++ b/src/arch/aarch64/hypervisor/handler.c
@@ -1069,7 +1069,7 @@
 		struct vcpu_locked current_locked;
 
 		current_locked = vcpu_lock(vcpu);
-		vcpu->regs.r[0] = ffa_interrupts_get(current_locked);
+		vcpu->regs.r[0] = api_interrupt_get(current_locked);
 		vcpu_unlock(&current_locked);
 		break;
 	}