Build: Convert mps2/an539 targets to modern cmake

Add cmake files to an539 target directory. Alter scatter files to
remove preprocessor shebang. Alter header files where include paths have
changed.

WARNING: This change will not build in isolation, it requires _all_
other cmake changes to successfully build. It is split out only for ease
of understanding.

Signed-off-by: Raef Coles <raef.coles@arm.com>
Change-Id: I3ab85c6911e2a9ede481e5c0ec957b413c997735
7 files changed