Currently every file in boot directory is copied over target /boot on
root file system and is usually inaccessible because appropriate boot
file system is mounted on top of it. Therefore remove /boot, which in
result will also save space on target root file system.
Signed-off-by: Tomasz Maciej Nowak <tomek_n@o2.pl>
(backported from 31075313bf69fff3803b7c1da1e0ed7e5773d999)