Fix docker buildx build (#630)

hack/ccm/Makefile

@@ -41,7 +41,7 @@ build-image-and-push-linux-ppc64le: init-buildx
 
 init-buildx:
 	# Ensure we use a builder that can leverage it (the default on linux will not)
-	docker buildx rm multiarch-multiplatform-builder
+	-docker buildx rm multiarch-multiplatform-builder
 	docker buildx create --use --name=multiarch-multiplatform-builder
 	docker run --rm --privileged multiarch/qemu-user-static --reset --credential yes --persistent yes
 	# Register gcloud as a Docker credential helper.