refactor: set vcpu in preempted state

The function `vcpu_set_processing_interrupt` is refactored
to set the preempted vcpu state as `VCPU_STATE_PREEMPTED`.

This refactor opens the possibility to drop other instances
in which the `VCPU_STATE_PREEMPTED` is used.
This is completed in the subsequent patches.

Signed-off-by: J-Alves <joao.alves@arm.com>
Change-Id: I02f5d92e15aa850b73ededea37fd7fbe5ba41a52
diff --git a/inc/hf/vcpu.h b/inc/hf/vcpu.h
index b50a578..92656ea 100644
--- a/inc/hf/vcpu.h
+++ b/inc/hf/vcpu.h
@@ -385,5 +385,6 @@
 				  uint8_t priority);
 void vcpu_interrupt_inject(struct vcpu_locked target_locked, uint32_t intid);
 void vcpu_set_processing_interrupt(struct vcpu_locked vcpu_locked,
-				   uint32_t intid, struct vcpu *preempted);
+				   uint32_t intid,
+				   struct vcpu_locked preempted_locked);
 void vcpu_enter_secure_interrupt_rtm(struct vcpu_locked vcpu_locked);