Keystone PM bus makes use of generic PM clock core backend. Since
generic PM clock core uses platform bus notifiers to track events like
ADD_DEVICE/DEL_DEVICE and to fill clock lists per each device, we need
to initialise Keystone PM domains before the platform devices have been
created.

Hence, fix it by moving keystone_pm_runtime_init() before platform
devices have been populated.
Reported-by: NGrygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: NSantosh Shilimkar <santosh.shilimkar@ti.com>