dcmihandler: use visitor to pull sensor values
dcmihandler: use visitor to pull sensor values

This will help upgrade us to using doubles in the future.

Change-Id: I94bb26fc43ae410a15402b4966e135d847a1fa33
Signed-off-by: James Feist <9f787ca2e294231a0bf80dc589f168b98eea7133@linux.intel.com>

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