fix(rss): clear the message buffer

Clear the MHU message buffer to remove assets from memory.

Signed-off-by: Tamas Ban <tamas.ban@arm.com>
Change-Id: I730e7b044eaf0bf517532a12146e4f542949544e
diff --git a/drivers/arm/rss/rss_comms.c b/drivers/arm/rss/rss_comms.c
index 8b5002f..5e224e1 100644
--- a/drivers/arm/rss/rss_comms.c
+++ b/drivers/arm/rss/rss_comms.c
@@ -142,6 +142,9 @@
 		VERBOSE("out_vec[%lu].buf=%p\n", idx, (void *)out_vec[idx].base);
 	}
 
+	/* Clear the MHU message buffer to remove assets from memory */
+	memset(&io_buf, 0x0, sizeof(io_buf));
+
 	seq_num++;
 
 	return return_val;