RTOS: Thread: Fix return value for signal_wait

Signal wait was always returning success even in case of error.

rtos/Thread.cpp

@@ -309,9 +309,10 @@ osEvent Thread::signal_wait(int32_t signals, uint32_t millisec) {
                 evt.status = (osStatus)osErrorValue;
                 break;
         }
-    }
+    } else {
         evt.status = (osStatus)osEventSignal;
         evt.value.signals = res;
+    }
 
     return evt;
 }