To make software license auditing simpler, use SPDX[0] license
identifiers instead of duplicating the license text in every file.

NOTE: Files that have been imported by FreeBSD have not been modified.

[0]: https://spdx.org/

Change-Id: I80a00e1f641b8cc075ca5a95b10607ed9ed8761a
Signed-off-by: dp-arm <dimitris.papastamos@arm.com>

Replaced placeholder implementation of plat_set_nv_ctr for FVP
platforms by a working one.

On FVP, the mapping of region DEVICE2 has been changed from RO to RW
to prevent exceptions when writing to the NV counter, which is
contained in this region.

Change-Id: I56a49631432ce13905572378cbdf106f69c82f57