powerpc/83xx/suspend: Clear deep_sleeping after devices resume

Currently 83xx PMC driver clears deep_sleeping variable very early,
before devices are resumed. This makes fsl_deep_sleep() unusable in
drivers' resume() callback.

Sure, drivers can store fsl_deep_sleep() value on suspend and use
the stored value on resume. But a better solution is to postpone
clearing the deep_sleeping variable, i.e. move it into finish()
callback.

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Acked-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>