test(ff-a): add tests for the FFA_RXTX_UNMAP ABI

Signed-off-by: Daniel Boulby <daniel.boulby@arm.com>
Change-Id: Id4d8cfd2f94ff15201de70a13eececf444d5e66e
diff --git a/include/runtime_services/ffa_helpers.h b/include/runtime_services/ffa_helpers.h
index a17f115..c3f6294 100644
--- a/include/runtime_services/ffa_helpers.h
+++ b/include/runtime_services/ffa_helpers.h
@@ -414,6 +414,7 @@
 smc_ret_values ffa_partition_info_get(const struct ffa_uuid uuid);
 smc_ret_values ffa_rx_release(void);
 smc_ret_values ffa_rxtx_map(uintptr_t send, uintptr_t recv, uint32_t pages);
+smc_ret_values ffa_rxtx_unmap(void);
 smc_ret_values ffa_mem_donate(uint32_t descriptor_length,
 			      uint32_t fragment_length);
 smc_ret_values ffa_mem_lend(uint32_t descriptor_length,