Add direct drive probing and setup support

This patch adds support to probe platform drivers for Ethos-U direct
device, parse the device tree entries, initialize and setup the
Ethos-U65/U85 NPU devices with appropriate security and privilege levels
for usage.

Signed-off-by: Rajasekaran Kalidoss <rajasekaran.kalidoss@arm.com>
Change-Id: I9b295f1d896afe75d8ee6a60e05d3ec4904482ee