bsp-pinned-repos.yml is included from all SystemReady Kas files so move
its inclusion to arm-bsp-extras.yml

Remove setting the ACS build target to core-image-minimal which was
mistakenly added in 4963c4ae.

Remove explicit inclusion of arm-bsp-extras.yml, which now duplicates
the inclusion from the Kconfig. Add arm-bsp-extras to the
Bsp-Image-Build-firmware build job where is was missing.

Signed-off-by: Peter Hoyes <peter.hoyes@arm.com>