Remove build-kernel helper script

Logic is available via scripts/build-package helper.

scripts/build-kernel

@@ -1,36 +0,0 @@
-#!/bin/bash
-if [ ! -f "Makefile" ]; then
-  echo "Makefile missing, This script needs to be executed inside the vyos-kernel package directory"
-  exit 1
-fi
-
-if grep -Fxq "KBUILD_OUTPUT" Makefile; then
-  echo "Wrong Makefile?, This script needs to be executed inside the vyos-kernel package directory"
-  exit 1
-fi
-
-
-# newer Kernel versions come with a "# SPDX-License-Identifier: GPL-2.0" identifier
-# as the first line in the file - use compatible approach with grep rather then sed
-VERSION=$(grep "^VERSION" Makefile | grep -Eo '[0-9]{1,4}')
-PATCHLEVEL=$(grep "^PATCHLEVEL" Makefile | grep -Eo '[0-9]{1,4}')
-SUBLEVEL=$(grep "^SUBLEVEL" Makefile | grep -Eo '[0-9]{1,4}')
-ARCH=$(dpkg --print-architecture)
-
-case "$ARCH" in
-    amd64)
-        make x86_64_vyos_defconfig
-        TARGETS="kernel_headers kernel_image"
-        # the following targets are not supported for Linux Kernels > 4.14 as
-        # they have been removed from the Makefile (commits 18afab8c1d3c2 &
-        # 22cba31bae9dc).
-        if [ ${PATCHLEVEL} -lt 14 ]; then
-            TARGETS+=" kernel_manual kernel_doc"
-        fi
-        CONCURRENCY_LEVEL=4 LOCALVERSION="" make-kpkg --rootcmd fakeroot --initrd --append_to_version -amd64-vyos --revision=$VERSION.$PATCHLEVEL.$SUBLEVEL-1+vyos1+current1 -j$(cat /proc/cpuinfo | grep processor | wc -l) ${TARGETS}
-    ;;
-
-    armhf)
-        make armhf_vyos_defconfig
-    ;;
-esac