mfd : Copy the db8500 gic setting to the prcmu

In the case we go to the retention mode, we decoupled the gic
in order to have the A9 core to reach a stable WFI state.
But we want the prcmu to wake up the A9 when the gic has a pending
irq which is done by copying the gic settings to the to the prcmu.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>