Add gitlab-ci.yaml

This is configured to build and test the following configurations:

* BUILD_ARCH: arm
* CONFIG: renesas_shmobile_defconfig
* CONFIG_LOC: cip-kernel-config
* DEVICES: r8a7743-iwg20d-q7 r8a7745-iwg22d-sodimm
* DTBS: r8a7743-iwg20d-q7-dbcm-ca.dtb r8a7745-iwg22d-sodimm-dbhd-ca.dtb

* BUILD_ARCH: arm64
* CONFIG: renesas_defconfig
* CONFIG_LOC: cip-kernel-config
* DEVICES: r8a774c0-ek874
* DTBS: r8a774c0-ek874.dtb

* BUILD_ARCH: arm
* CONFIG: shmobile_defconfig
* CONFIG_LOC: intree
* DEVICES: r8a7743-iwg20d-q7 r8a7745-iwg22d-sodimm
* DTBS: r8a7743-iwg20d-q7-dbcm-ca.dtb r8a7745-iwg22d-sodimm-dbhd-ca.dtb

Over time support will be added for all CIP supported architectures and
configurations.

At the moment only simple boot tests are run. Real tests will be added in
the future

Signed-off-by: Chris Paterson <chris.paterson2@renesas.com>
4 jobs for chris/linux-4.19.y-cip-ci-test in 20 minutes and 6 seconds (queued for 15 seconds)