Make SCMI sensor protocol register with the notification core.

Link: https://lore.kernel.org/r/20200701155348.52864-8-cristian.marussi@arm.comReviewed-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: NCristian Marussi <cristian.marussi@arm.com>
Signed-off-by: NSudeep Holla <sudeep.holla@arm.com>