ethernet_interface: Fix gateway entry emission

When you emit both an IPv4 and IPv6 gateway, the current logic ends up
writing out something like

[Route]
Gateway=10.0.0.1
Gateway=fe80::1

This is not valid syntax for a [Route] section as you only get to define
a single route per section. We need to instead write out two sections
like

[Route]
Gateway=10.0.0.1
[Route]
Gateway=fe80::1

Change-Id: Iaf42d7f732f16cd7503f3cdef750621b23d59161
Signed-off-by: William A. Kennington III <wak@google.com>
1 file changed