HID: roccat: fix use-after-free in roccat_report_event

In the Linux kernel, the following vulnerability has been resolved: HID: roccat: fix use-after-free in roccat_report_event roccat_report_event() iterates over the device->readers list without holding the readers_lock. This allows a concurrent roccat_release() to remove and free a reader while it's still being accessed, leading to a use-after-free. Protect the readers list traversal with the readers_lock mutex.