[BUG] drivers/gpio: some possible sleep-in-atomic bugs

[Jia-Ju Bai]

According to drivers/gpio/gpio-grgpio.c, the kernel module may sleep 
under a spinlock.
The function call paths are:
grgpio_remove (acquire the spinlock)
  gpiochip_remove
    gpiochip_sysfs_unregister
      device_unregister --> may sleep
      mutex_lock --> may sleep
grgpio_remove (acquire the spinlock)
  gpiochip_remove
    gpiochip_sysfs_unregister
      gpiod_free
        __gpiod_free
          gpiod_unexport
            device_unregister --> may sleep
            mutex_lock --> may sleep

grgpio_remove (acquire the spinlock)
  irq_domain_remove
    mutex_lock --> may sleep

grgpio_irq_map (acquire the spinlock)
  request_irq --> may sleep

grgpio_irq_unmap (acquire the spinlock)
  free_irq --> may sleep


I do not find a good way to fix them, so I only report.
These possible bugs is found by my static analysis tool (DSAC) and 
checked by my code review.


Thanks,
Jia-Ju Bai