Fail if trace.h is included without TRACE_LEVEL

To avoid hiding errors, fail if a component includes trace.h,
but TRACE_LEVEL is not set.

Change-Id: Ia30e42c745af5b521194ffd32965a930fc490b66
Signed-off-by: Gabor Toth <gabor.toth2@arm.com>
diff --git a/components/common/trace/include/trace.h b/components/common/trace/include/trace.h
index 4395e41..1495374 100644
--- a/components/common/trace/include/trace.h
+++ b/components/common/trace/include/trace.h
@@ -20,7 +20,7 @@
 #define TRACE_LEVEL_DEBUG	(3)
 
 #ifndef TRACE_LEVEL
-#define TRACE_LEVEL	TRACE_LEVEL_ERROR
+#error "Trace level is not defined!"
 #endif /* TRACE_LEVEL */
 
 /**