evdev: Fix select() call

It's not guaranteed that the eventfd is smaller than the monitor fd,
because fds are not always monotonically allocated. To select()
correctly in all cases, use the max between the monitor fd and eventfd.

Source/Core/InputCommon/ControllerInterface/evdev/evdev.cpp

@@ -72,7 +72,7 @@ static void HotplugThreadFunc()
     FD_SET(monitor_fd, &fds);
     FD_SET(s_wakeup_eventfd, &fds);
 
-    int ret = select(monitor_fd + 1, &fds, nullptr, nullptr, nullptr);
+    int ret = select(std::max(monitor_fd, s_wakeup_eventfd) + 1, &fds, nullptr, nullptr, nullptr);
     if (ret < 1 || !FD_ISSET(monitor_fd, &fds))
       continue;