[BUG] atmel_ssc_dai: a possible sleep-in-atomic bug in atmel_ssc_shutdown

According to sound/soc/atmel/atmel_ssc_dai.c, the driver may sleep under 
a spinlock.
The function call path is:
atmel_ssc_shutdown (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