usb: storage: realtek_cr: fix use-after-free on disconnect

In the Linux kernel, the following vulnerability has been resolved: usb: storage: realtek_cr: fix use-after-free on disconnect realtek_cr_destructor() calls timer_delete() before the chip containing the timer is freed. The timer callback may still be running and can rearm itself, resulting in a use-after-free. Use timer_shutdown_sync() to wait for the callback and prevent further rearming. Do this unconditionally because ss_en may be changed after the timer is armed. Move timer_setup() into init_realtek_cr() so the timer is initialized before any failure path can invoke the destructor. Found by static analysis.