This way we don't depend on the permissions of files under boot/ or fs/,
which aren't tracked.
While we're at it, change all 'cp' usages into 'install' with the
correct mode for each file.
Signed-off-by: Guido Martínez <guido@vanguardiasur.com.ar>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>