refactor(ffa): remove `plat` prefix

Rename files to remove the `plat` prefix and replace with a
module-specific prefix.

Change-Id: Ie64cefcdf91da7b20e520828d8e234af12ab5c85
Signed-off-by: Karl Meakin <karl.meakin@arm.com>
diff --git a/inc/hf/ffa/direct_messaging.h b/inc/hf/ffa/direct_messaging.h
index d19e758..eb87da8 100644
--- a/inc/hf/ffa/direct_messaging.h
+++ b/inc/hf/ffa/direct_messaging.h
@@ -12,26 +12,26 @@
 #include "hf/vm.h"
 
 /** Check validity of a FF-A direct message request. */
-bool plat_ffa_is_direct_request_valid(struct vcpu *current,
-				      ffa_id_t sender_vm_id,
-				      ffa_id_t receiver_vm_id);
+bool ffa_direct_msg_is_direct_request_valid(struct vcpu *current,
+					    ffa_id_t sender_vm_id,
+					    ffa_id_t receiver_vm_id);
 
 /** Check validity of a FF-A direct message response. */
-bool plat_ffa_is_direct_response_valid(struct vcpu *current,
-				       ffa_id_t sender_vm_id,
-				       ffa_id_t receiver_vm_id);
+bool ffa_direct_msg_is_direct_response_valid(struct vcpu *current,
+					     ffa_id_t sender_vm_id,
+					     ffa_id_t receiver_vm_id);
 
-bool plat_ffa_is_direct_request_supported(struct vm *sender_vm,
-					  struct vm *receiver_vm,
-					  uint32_t func);
+bool ffa_direct_msg_is_direct_request_supported(struct vm *sender_vm,
+						struct vm *receiver_vm,
+						uint32_t func);
 
-bool plat_ffa_direct_request_forward(ffa_id_t receiver_vm_id,
-				     struct ffa_value args,
-				     struct ffa_value *ret);
+bool ffa_direct_msg_direct_request_forward(ffa_id_t receiver_vm_id,
+					   struct ffa_value args,
+					   struct ffa_value *ret);
 
-void plat_ffa_wind_call_chain_ffa_direct_req(
+void ffa_direct_msg_wind_call_chain_ffa_direct_req(
 	struct vcpu_locked current_locked,
 	struct vcpu_locked receiver_vcpu_locked, ffa_id_t sender_vm_id);
 
-void plat_ffa_unwind_call_chain_ffa_direct_resp(
+void ffa_direct_msg_unwind_call_chain_ffa_direct_resp(
 	struct vcpu_locked current_locked, struct vcpu_locked next_locked);