Fix the snmp parameter in NetworkProtocol

This should be the configuration information of snmpagent. Now
we have "snmp trap" functionality in openbmc,we don't have SNMP
agent functionality. So the parameters belonging to the agent
such as port are removed here.

Signed-off-by: Xiaochao Ma <maxiaochao@inspur.com>
Change-Id: I2d684b63d79ac1dc00bce0d2e0bd48e5a315f258