ostree-kernel-initramfs: Simplify bbappends

To reduce redundancy of the main code and explain why we need this
bbappend.

BugzID: 74466

bbappends/sota/recipes-sota/ostree-kernel-initramfs/ostree-kernel-initramfs_%.bbappend

@@ -1,14 +1,6 @@
+# The main recipe is expecting the fitimage to be built direclty
+# by virtual/kernel. But in our case virtual/kernel is building a
+# zImage/Image and we pack the fitimage in netmodule-fitimage
+
 do_install[depends] += " netmodule-fitimage:do_deploy"
-
-do_install() {
-	kerneldir=${D}${KERNEL_BUILD_ROOT}${KERNEL_VERSION}
-	install -d $kerneldir
-
-	cp ${DEPLOY_DIR_IMAGE}/${OSTREE_KERNEL} $kerneldir/vmlinuz
-
-	if [ -n "${INITRAMFS_IMAGE}"  ]; then
-		# this is a hack for ostree not to override init= in kernel cmdline -
-		# make it think that the initramfs is present (while it is in FIT image)
-		touch $kerneldir/initramfs.img
-	fi
-}
+KERNEL_IMAGETYPE = "fitImage"