drm/ci: fix DEBIAN_ARCH and get amdgpu probing

amdgpu driver wasn't loading because amdgpu firmware wasn't being
installed in the rootfs due to the wrong DEBIAN_ARCH variable.

rename ARCH to DEBIAN_ARCH also, so we don't have the confusing
DEBIAN_ARCH, KERNEL_ARCH and ARCH.

Signed-off-by: Helen Koike <helen.koike@collabora.com>
Reviewed-by: David Heidelberg <david.heidelberg@collabora.com>
Link: https://lore.kernel.org/r/20231024004525.169002-3-helen.koike@collabora.com
Signed-off-by: Maxime Ripard <mripard@kernel.org>

drivers/gpu/drm/ci/test.yml

@@ -23,7 +23,7 @@
     - .lava-test:arm32
   variables:
     HWCI_TEST_SCRIPT: "/install/igt_runner.sh"
-    ARCH: "armhf"
+    DEBIAN_ARCH: "armhf"
   dependencies:
     - testing:arm32
   needs:
@@ -38,7 +38,7 @@
     - .lava-test:arm64
   variables:
     HWCI_TEST_SCRIPT: "/install/igt_runner.sh"
-    ARCH: "arm64"
+    DEBIAN_ARCH: "arm64"
   dependencies:
     - testing:arm64
   needs:
@@ -53,7 +53,7 @@
     - .lava-test:x86_64
   variables:
     HWCI_TEST_SCRIPT: "/install/igt_runner.sh"
-    ARCH: "x86_64"
+    DEBIAN_ARCH: "amd64"
   dependencies:
     - testing:x86_64
   needs: