feat(cactus): memory sharing flags in test commands

Extend the test command CACTUS_MEM_SEND_CMD:
- To include the flags for the retriever to use in transaction
descriptor to the FFA_MEM_RETRIEVE_REQ.
- Number of words cactus should write to the shared page after
retrieving it.
- Check if memory has been cleared after mapping to cactus address space
if clear memory flag was propagated in the command arguments.

Signed-off-by: J-Alves <joao.alves@arm.com>
Change-Id: I825b0f766bd7132a3488cdd17d83fce85adf4a5a
diff --git a/include/runtime_services/spm_common.h b/include/runtime_services/spm_common.h
index 4ec71fc..398d01a 100644
--- a/include/runtime_services/spm_common.h
+++ b/include/runtime_services/spm_common.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021, Arm Limited. All rights reserved.
+ * Copyright (c) 2021-2022, Arm Limited. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -129,7 +129,7 @@
 bool memory_retrieve(struct mailbox_buffers *mb,
 		     struct ffa_memory_region **retrieved, uint64_t handle,
 		     ffa_id_t sender, ffa_id_t receiver,
-		     uint32_t mem_func);
+		     uint32_t mem_func, ffa_memory_region_flags_t flags);
 
 /**
  * Helper to conduct a memory relinquish. The caller is usually the receiver,