refactor(rse): change all occurrences of RSS to RSE

Changes all occurrences of "RSS" and "rss" in the code and build files
to "RSE" and "rse".

Signed-off-by: Tamas Ban <tamas.ban@arm.com>
Change-Id: I9f72ad36ec233d7eaac3ce9e2f2b010130e1fa94
diff --git a/include/drivers/arm/rse_comms.h b/include/drivers/arm/rse_comms.h
index b96c79f..e4169a5 100644
--- a/include/drivers/arm/rse_comms.h
+++ b/include/drivers/arm/rse_comms.h
@@ -5,11 +5,11 @@
  *
  */
 
-#ifndef RSS_COMMS_H
-#define RSS_COMMS_H
+#ifndef RSE_COMMS_H
+#define RSE_COMMS_H
 
 #include <stdint.h>
 
-int rss_comms_init(uintptr_t mhu_sender_base, uintptr_t mhu_receiver_base);
+int rse_comms_init(uintptr_t mhu_sender_base, uintptr_t mhu_receiver_base);
 
-#endif /* RSS_COMMS_H */
+#endif /* RSE_COMMS_H */