Rewrite makefile to use out/ dir

docker/initramfs.Dockerfile

@@ -1,11 +1,5 @@
 ARG TAG=dev
 ARG DOCKER_IMAGE_ROOT=monok8s
-FROM --platform=$BUILDPLATFORM ${DOCKER_IMAGE_ROOT}/kernel-build:${TAG} AS kernel
-
-# Selective mods
-RUN mkdir /out/selected-mods
-COPY initramfs/selective-mods.sh /
-RUN /selective-mods.sh /out/rootfs/lib/modules/$(ls /out/rootfs/lib/modules/) /out/selected-mods
 
 FROM --platform=$BUILDPLATFORM ${DOCKER_IMAGE_ROOT}/build-base:${TAG} AS build
 
@@ -35,7 +29,11 @@ COPY initramfs/init init
 RUN chmod +x init
 RUN mkdir -p bin sbin etc proc sys dev lib usr/bin usr/sbin
 
-COPY --from=kernel /out/selected-mods/* ./lib/
+# Selective mods
+RUN mkdir -p /out/selected-mods /out/kernel
+COPY initramfs/selective-mods.sh /
+COPY out/rootfs /out/rootfs
+RUN /selective-mods.sh /out/rootfs/lib/modules/$(ls /out/rootfs/lib/modules/) ./lib/
 
 RUN find . -print0 | cpio --null -ov --format=newc | gzip -9 > ../initramfs.cpio.gz