arm: async uart writes & fixes

arm/trace.cc

@@ -32,7 +32,7 @@ void dump() {
 
     for (TraceEvent event : buffer) {
         itoa(static_cast<int>(event), number);
-        UartSendCrash(number);
+        UartWriteCrash(number);
     }
 }
 }  // namespace tracing