mfd: arizona: Add better support for system suspend

Allow the chip to completely power off if we enter runtime suspend and
there is no jack detection active. This is helpful for systems where
system suspend might remove the supplies to the CODEC, without informing
us. Note the powering off is done in runtime suspend rather than system
suspend, because we need to hold reset until the first time DCVDD is
powered anyway (which would be in runtime resume), and we might as well
save the extra power.

Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>