transporthandler: Convert ints to enum
transporthandler: Convert ints to enum

We want to be able to identify unique LanParams for each of the
different sub-queries. These make more semantic sense as an enum than
individual ints.

Tested:
    Built and run through unit test suite.

Change-Id: Ieb304f2f866215776e8d3e264b07ea110c639efc
Signed-off-by: William A. Kennington III <30fff5198f4d10ca1117e5f3ec82f3b4b8900d81@google.com>

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