Build: Disable NSPE log by default with eRPC

Make the logging from NSPE optional and disable it by default
when eRPC is used to prevent message collision.

Change-Id: I517c334fe0ea6d79572b499947f2c159e4a10707
Signed-off-by: David Vincze <david.vincze@arm.com>
diff --git a/lib/log/tfm_log.h b/lib/log/tfm_log.h
index 5563434..5d5e649 100644
--- a/lib/log/tfm_log.h
+++ b/lib/log/tfm_log.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019-2020, Arm Limited. All rights reserved.
+ * Copyright (c) 2019-2024, Arm Limited. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  *
@@ -12,6 +12,10 @@
 
 /* Functions and macros in this file is for 'thread mode' usage. */
 
+#ifdef TFM_NS_LOG
 #define LOG_MSG(...) tfm_log_printf(__VA_ARGS__)
+#else
+#define LOG_MSG(...)
+#endif
 
 #endif /* __TFM_LOG_H__ */