drivers: usb: host: Fix deadlock in oxu_bus_suspend()

In the Linux kernel, the following vulnerability has been resolved:

drivers: usb: host: Fix deadlock in oxu_bus_suspend()

There is a deadlock in oxu_bus_suspend(), which is shown below:

(Thread 1) | (Thread 2)

| timer_action()

oxu_bus_suspend() | mod_timer()

spin_lock_irq() //(1) | (wait a time)

... | oxu_watchdog()

del_timer_sync() | spin_lock_irq() //(2)

(wait timer to stop) | ...

We hold oxu->lock in position (1) of thread 1, and use

del_timer_sync() to wait timer to stop, but timer handler

also need oxu->lock in position (2) of thread 2. As a result,

oxu_bus_suspend() will block forever.

This patch extracts del_timer_sync() from the protection of

spin_lock_irq(), which could let timer handler to obtain

the needed lock.