Remove leftover todo related to the dhcpcd support

With commit [1] support for dhcpcd client was added to tempest
but there was not cleaned one of the TODO notes related to that.
So this patch simply cleans that left over.

[1] https://review.opendev.org/c/openstack/tempest/+/871270

Change-Id: I0c94ac5e7fd7b6da0fd051b9ff7d4c226be73f76
1 file changed