ci/lava: Only deploy kernel-modules when needed

Not all LAVA jobs appear to require kernel modules, so only apply the
kernel-modules overlay when HWCI_KERNEL_MODULES is explicitly set.

Signed-off-by: Valentine Burley <valentine.burley@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/35129>

.gitlab-ci/lava/lava-submit.sh

@@ -79,6 +79,15 @@ if [ -n "${LAVA_FIRMWARE:-}" ]; then
         )
     done
 fi
+if [ -n "${HWCI_KERNEL_MODULES:-}" ]; then
+	LAVA_EXTRA_OVERLAYS+=(
+		- append-overlay
+		  --name=kernel-modules
+		  --url="${KERNEL_IMAGE_BASE}/${DEBIAN_ARCH}/modules.tar"
+		  --path="/"
+		  --format=tar
+	)
+fi
 
 PYTHONPATH=/ /lava/lava_job_submitter.py \
 	--farm "${FARM}" \
@@ -110,11 +119,6 @@ PYTHONPATH=/ /lava/lava_job_submitter.py \
 		--compression=zstd \
 		--path="${CI_PROJECT_DIR}" \
 		--format=tar \
-	- append-overlay \
-		--name=kernel-modules \
-		--url="${KERNEL_IMAGE_BASE}/${DEBIAN_ARCH}/modules.tar" \
-		--path="/" \
-		--format=tar \
 	"${LAVA_EXTRA_OVERLAYS[@]}" \
 	- submit \
 	>> results/lava.log