sdbusplus: replace message::variant with std::variant
sdbusplus: replace message::variant with std::variant

Signed-off-by: Patrick Williams <cbb7353e6d953ef360baf960c122346276c6e320@stwcx.xyz>
Change-Id: I18f79cafeb469f1b3dd56d6a05f3aa919269ddf9

openbmc/phosphor-networkd,openbmc/phosphor-networkd