SPCI: SPCI_YIELD.

Adapted hf_vcpu_yield to conform with the spci_yield specification.

Change-Id: I7ad11e83f068a09a19fd930dcead787b5a22e498
diff --git a/inc/vmapi/hf/call.h b/inc/vmapi/hf/call.h
index 6d36d54..aaa2fa7 100644
--- a/inc/vmapi/hf/call.h
+++ b/inc/vmapi/hf/call.h
@@ -28,7 +28,6 @@
 #define HF_VM_GET_COUNT         0xff01
 #define HF_VCPU_GET_COUNT       0xff02
 #define HF_VCPU_RUN             0xff03
-#define HF_VCPU_YIELD           0xff04
 #define HF_VM_CONFIGURE         0xff05
 #define HF_MAILBOX_CLEAR        0xff08
 #define HF_MAILBOX_WRITABLE_GET 0xff09
@@ -84,10 +83,11 @@
 
 /**
  * Hints that the vcpu is willing to yield its current use of the physical CPU.
+ * This call always returns SPCI_SUCCESS.
  */
-static inline void hf_vcpu_yield(void)
+static inline int64_t spci_yield(void)
 {
-	hf_call(HF_VCPU_YIELD, 0, 0, 0);
+	return hf_call(SPCI_YIELD_32, 0, 0, 0);
 }
 
 /**