SPCI: SPCI_FEATURES implementation.

Change-Id: I1bb3e32808d503ee75303a5e70b41645b2d7e86b
diff --git a/inc/hf/api.h b/inc/hf/api.h
index 406b620..024973e 100644
--- a/inc/hf/api.h
+++ b/inc/hf/api.h
@@ -66,3 +66,4 @@
 	struct vm_locked to_locked, struct vm_locked from_locked,
 	struct spci_memory_region *memory_region, uint32_t memory_to_attributes,
 	enum spci_memory_share share);
+struct spci_value api_spci_features(uint32_t function_id);