Run getty on all /dev/ttyC* apart from ttyC0, since it might conflict

with /dev/console.
Feedback from and ok kettenis@

src/etc/etc.arm64/ttys

@@ -1,9 +1,21 @@
 #
-#	$OpenBSD: ttys,v 1.1 2017/01/11 17:05:29 patrick Exp $
+#	$OpenBSD: ttys,v 1.2 2020/03/13 13:14:40 patrick Exp $
 #
 # name	getty				type	status		comments
 #
 console	"/usr/libexec/getty std.115200"	vt220	on  secure
+ttyC0	"/usr/libexec/getty std.9600"	vt220	off secure
+ttyC1	"/usr/libexec/getty std.9600"	vt220	on  secure
+ttyC2	"/usr/libexec/getty std.9600"	vt220	on  secure
+ttyC3	"/usr/libexec/getty std.9600"	vt220	on  secure
+ttyC4	"/usr/libexec/getty std.9600"	vt220	off secure
+ttyC5	"/usr/libexec/getty std.9600"	vt220	on  secure
+ttyC6	"/usr/libexec/getty std.9600"	vt220	off secure
+ttyC7	"/usr/libexec/getty std.9600"	vt220	off secure
+ttyC8	"/usr/libexec/getty std.9600"	vt220	off secure
+ttyC9	"/usr/libexec/getty std.9600"	vt220	off secure
+ttyCa	"/usr/libexec/getty std.9600"	vt220	off secure
+ttyCb	"/usr/libexec/getty std.9600"	vt220	off secure
 tty00	"/usr/libexec/getty std.115200"	unknown off secure
 tty01	"/usr/libexec/getty std.9600"	unknown off secure
 tty02	"/usr/libexec/getty std.9600"	unknown off