rdv3*: use kvm-ut repo from reference-design gitlab space

Point the kvm-unit-test to the repo infra-solutions/reference-design
gitlab space. This will allow the repo to carry patches specific to the
Neoverse Reference Design project.

Change-Id: Ieaf11f9219b4fd1304b5d93076aa563c2a5b9a08
Signed-off-by: Vijayenthiran Subramaniam <vijayenthiran.subramaniam@arm.com>