userspace/snmpd: change values of "first read" defines (non compatible change)

To make SNMP return objects more consistent, "first read" defines were changed
for following objects in wrsNetworkingStatusGroup:
--wrsEndpointStatus
--wrsSwcoreStatus
--wrsRTUStatus

Signed-off-by: Adam Wujek <adam.wujek@cern.ch>