[BUG] sbni: a possible sleep-in-atomic bug in sbni_close

[Jia-Ju Bai]

According to drivers/net/wan/sbni.c, the driver may sleep under a spinlock.
The function call path is:
sbni_close (acquire the spinlock)
  free_irq --> may sleep

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


Thanks,
Jia-Ju Bai