Fix typos.

Change-Id: I3955318b4a0fd6fa6e10dbcfd20f2d675075d467
diff --git a/inc/vmapi/hf/call.h b/inc/vmapi/hf/call.h
index 7f229d2..7b523e2 100644
--- a/inc/vmapi/hf/call.h
+++ b/inc/vmapi/hf/call.h
@@ -131,7 +131,7 @@
  *
  * Returns 0 on success, or -1 if the intid is invalid.
  */
-static inline uint64_t hf_enable_interrupt(uint32_t intid, bool enable)
+static inline int64_t hf_enable_interrupt(uint32_t intid, bool enable)
 {
 	return hf_call(HF_ENABLE_INTERRUPT, intid, enable, 0);
 }