remove configuration option 'ipv4mtu'

Specifying the MTU in a per-device configuration file is in
general incorrect because different networks have different MTUs.

Carriers or operators that want to lower the MTU can lower the
IPv6 MTU (from which the IPv4 MTU is automatically calculated),
or set the MTU manually from Nat464Xlat or ConnectivityService.
Doing it this way has the benefit of supporting different MTUs
for different networks.

Test: builds
Bug: 144730808
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: Ia6005421e81fc0007067d9774e28f9aae64d1160
1 file changed