linux-pam: install login.pam from here

linux-pam: install login.pam from here

Instead of installing login.pam (/etc/pam.d/login) from util-linux
conditionally do so unconditionally from linux-pam.
If busybox login is pam-enabled (linux-pam package enabled) it will be
required, otherwise it will lead to a system where login won't work, and
if util-linux is enabled it will supercede busybox login and will be
necesarry regardless.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>