ci(drtm): add DRTM build for FVP platform

Added a DRTM build in l1-build group as well as
in the coverity.

Change-Id: Icf279d64bfefd5cc63836486a0338268cf8a49a1
Signed-off-by: Manish V Badarkhe <Manish.Badarkhe@arm.com>
4 files changed