systemd: always depend on the explicit serial console units

The systemd-serialgetty recipe generates explicit units for consoles
that are defined in SERIAL_CONSOLES, and if that variable is not defined
then just produces an empty package.

Even when systemd has been configured to use the getty generator, if
there are explicit consoles defined then we should respect them.  Don't
conditionalise the dependency on systemd-serialgetty so that we always
pull in the explicit consoles.

(From OE-Core rev: 6ec2c52b938302b894f119f701ffcf0a847eee85)

Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-core/systemd/systemd_257.4.bb

@@ -754,7 +754,7 @@ FILES:${PN} = " ${base_bindir}/* \
 FILES:${PN}-dev += "${base_libdir}/security/*.la ${datadir}/dbus-1/interfaces/ ${sysconfdir}/rpm/macros.systemd"
 
 RDEPENDS:${PN} += "kmod dbus util-linux-mount util-linux-umount udev (= ${EXTENDPKGV}) systemd-udev-rules util-linux-agetty util-linux-fsck util-linux-swaponoff util-linux-mkswap"
-RDEPENDS:${PN} += "${@bb.utils.contains('PACKAGECONFIG', 'serial-getty-generator', '', 'systemd-serialgetty', d)}"
+RDEPENDS:${PN} += "systemd-serialgetty"
 RDEPENDS:${PN} += "volatile-binds"
 
 RRECOMMENDS:${PN} += "${PN}-extra-utils \