fix(coverity_tf_conf.py): exclude GIC600AE FMU files

This patch excludes the GIC600 AE FMU source files from the coverity
scans as they are not used by any upstream platform. This patch fixes
the CI failures for newly added GIC600 AE FMU driver files.

Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>
Change-Id: I5a10603ef971cbfb7bf84c30c2a9cb550d707b9e
1 file changed