Add string literals for hwmon types and entries
Add string literals for hwmon types and entries

Enable participation in constexpr.

Change-Id: I182adcf866909e3d7d44b0e4cadedda362f4ad50
Signed-off-by: Brad Bishop <713d098c0be4c8fd2bf36a94cd08699466677ecd@fuzziesquirrel.com>

openbmc/phosphor-hwmon,openbmc/phosphor-hwmon