serial: amba-pl011: cancel RS485 hrtimers after freeing IRQ

In the Linux kernel, the following vulnerability has been resolved: serial: amba-pl011: cancel RS485 hrtimers after freeing IRQ The RS485 trigger hrtimers are embedded in the devm-managed port and can fire after it is freed. The IRQ handler can arm a timer, so free the IRQ first and then cancel both timers. Complete the RS485 stop without arming a timer, and cancel the timers in remove() for the suspend-then-unbind path, where shutdown is not called. This issue was found by an in-house static analysis tool.