grub-config: Fix paths of default linux

opt/grub-config

@@ -11,12 +11,14 @@ if [ ! -f "$DEFAULT_LINUX" ]; then
   # in cases where it’s a .gz or .xz or whatever
   DEFAULT_LINUX=$(find /boot -type l -name "vmlinu*" 2>/dev/null | sort | head -n1)
 fi
+DEFAULT_LINUX="$(sed 's|^/boot/||' <<< "$DEFAULT_LINUX")"
 
 DEFAULT_INITRAMFS=/boot/initramfs.img
 if [ ! -f "$DEFAULT_INITRAMFS" ]; then
   # hope to find anything named initramfs or initrd
   DEFAULT_INITRAMFS=$(find /boot -type l -name "init*" 2>/dev/null | sort | head -n1)
 fi
+DEFAULT_INITRAMFS="$(sed 's|^/boot/||' <<< "$DEFAULT_INITRAMFS")"
 
 function make_menuentry {
   # $1 is the kernel path