jammy-amd64-tf-a-build: Install ArmClang 6.18 in the image

This is first version which supports UBL licensing and thus required to
leverage it.

Also, the TF-A build process kinda requires 6.18, except for some reason,
it was worked around by linking to 6.17 instead, see revision
013f633fd1804.

Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>
Change-Id: I5ab7029a35abf0ba741de3a94ed4d01a59ca27ec
3 files changed