arm/dt: 9625: Enable delay before entering LPM

Set the parameter in 9625 DTS file, to wait one second before
entering LPM after USB cable disconnect.

This is needed to resolve race condition in which USB driver
tries to access USB HW shortly after the controller is put into LPM.

Change-Id: I9c207b8e3ff398fafafae086d86cf91c91b4c775
Signed-off-by: Amit Blay <ablay@codeaurora.org>