busybox: add klogd service to FILES

busybox: add klogd service to FILES

busybox syslog.service file contains:
  Also=busybox-klogd.service

That's why busybox-klog.service got automatically added to
FILES:busybox-syslog. Since this incorrect auto adding feature gets
dropped from systemd.bbclass this needs to be added explicitly.

Signed-off-by: Adrian Freihofer <adrian.freihofer@siemens.com>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>