Wrong serial console device in inittab

[mstarostik]

Version (k3OS / kernel)
k3os version v0.10.1
5.0.0-43-generic #47~18.04.1 SMP Wed Apr 1 16:27:01 UTC 2020

Architecture
x86_64

Describe the bug
After installing with k3os.install.tty=ttyS1 and /etc/inittab gets this last line:
ttyS1::respawn:/sbin/getty -L ttyS0 115200 vt100
Note the discrepancy between ttyS1 in the line's tag and ttyS0 in the argument to getty.
Result: no login prompt on the actual serial console

To Reproduce
Try to install k3OS for use with a serial console on anything but ttyS0

Expected behavior
Both mentions of the tty device in /etc/inittab should match up to enable serial login

Actual behavior
getty launched on the wrong device

Additional context
One line fix in https://github.com/rancher/k3os/blob/master/overlay/libexec/k3os/boot line 20 should do it.
On a side note, there should be a way to pass a baudrate to install.sh / k3os.install.tty to get e.g. console=ttyS1,115200 into the kernel cmdline. Probably requires various changes where console= arg is tested with -e etc.