Correct the IPv6 Router Address Configuration command
Correct the IPv6 Router Address Configuration command

The IPv6 Router Address Configuration Get/Set LAN command was not
reporting or modifying the correct portion of the networking
system. This command is intended to configure the Routing
Advertisement feature of IPv6. It is not a direct reflection of the
DHCP state.

Systemd-networkd manages the Routing Advertisement via the
IPv6AcceptRA parameter, which according to the networkd documentaion,
enables/disables IPv6 DHCP functionality.

Tested:
Issued "ipmitool raw 12 2 3 64 0 0" and was able to read the current
state of the IPv6AcceptRA variable.
Issued "ipmitool raw 12 1 3 64 2" and saw the configuration file for
the channel change, and the addition of a new IPv6 address to the
network device.
Issued "ipmitool raw 12 1 3 64 0" and saw that configuration file for
the channel change, and the removal of the IPv6 address from the
network device.

Change-Id: Id01441f88ccc9d56449ab8115f4855de74e80cfc
Signed-off-by: Johnathan Mantey <0048b8e2f791bacb0830da233adbf1612889167c@intel.com>

openbmc/phosphor-host-ipmid,openbmc/phosphor-host-ipmid,openbmc/phosphor-host-ipmid