POSIX Drivers: Clear disconnected status when closing

This allows us to properly re-open if we were
previously disconnected.

platform/posix/ftdi.cpp

@@ -108,6 +108,7 @@ bool FTDI::close() {
 	while(writeQueue.try_dequeue(flushop)) {}
 
 	closing = false;
+	disconnected = false;
 	return ret;
 }