of: platform: Batch fwnode parsing when adding all top level devices

The fw_devlink_pause() and fw_devlink_resume() APIs allow batching the
parsing of the device tree nodes when a lot of devices are added. This
will significantly cut down parsing time (as much a 1 second on some
systems). So, use them when adding devices for all the top level device
tree nodes in a system.

Signed-off-by: Saravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20200515053500.215929-5-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>