package/systemd: use util-linux' agetty, drop patch

package/systemd: use util-linux' agetty, drop patch

We currently have a patch that replaces the use of (hard-coded) agetty
in systemd, to use just plain getty. That patch dates back to commit
f4a5eed474c (Add the systemd package), when util-linux was not a
dependency, and we relied on busybox to actually provide getty.

But nowadays, util-linux is a mandatory dependency of systemd anyway.
agetty is about 42KiB, while busybox' getty is around 5KiB (give or
take). That's an extra ~40KiB, but it has to be balanced against the
rest of the system: systemd only runs on a glibc system, needs dbus and
thus expat, and kmod, that a ~40KiB overhead is barely noticeable (a
miminal systemd setup with nothing enabled, on ARM, is already ~20MiB)

So, drop our agetty-dropping patch, and forcibly enable agetty in
util-linux.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Adam Duskett <aduskett@gmail.com>
Cc: Maxime Hadjinlian <maxime.hadjinlian@gmail.com>
Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>