genirq: Move irq resource handling out of spinlocked region

Aside of being conceptually wrong, there is also an actual (hard to
trigger and mostly theoretical) problem.

CPU0				CPU1
free_irq(X)			interrupt X
				spin_lock(desc->lock)
				wake irq thread()
				spin_unlock(desc->lock)
spin_lock(desc->lock)
remove action()
shutdown_irq()			
release_resources()		thread_handler()
spin_unlock(desc->lock)		  access released resources.

synchronize_irq()

Move the release resources invocation after synchronize_irq() so it's
guaranteed that the threaded handler has finished.

Move the resource request call out of the desc->lock held region as well,
so the invocation context is the same for both request and release.

This solves the problems with those functions on RT as well.
 
Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: Marc Zyngier <[email protected]>
Cc: Heiko Stuebner <[email protected]>
Cc: Julia Cartwright <[email protected]>
Cc: Linus Walleij <[email protected]>
Cc: Brian Norris <[email protected]>
Cc: Doug Anderson <[email protected]>
Cc: [email protected]
Cc: John Keeping <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]

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