lg2: conversion: reduce std::forward clutter
lg2: conversion: reduce std::forward clutter

It was observed in another repository that if the same std::string
was passed twice into lg2 function that clang-tidy would complain
about a potential use-after-realloc due to the 'string.data()' call
for the first instance followed by a 'std::forward' on the second
instance.  I don't think there was actually any issue with that, but
we don't really leverage r-value references in this code because there
is never an opportunity to 'std::move' any contents.  Remove the
clutter of 'std::forward' everywhere and simply rely on l-value
references, which is all the code needs anyhow.  This also placated
clang-tidy's memory use checker.

Signed-off-by: Patrick Williams <cbb7353e6d953ef360baf960c122346276c6e320@stwcx.xyz>
Change-Id: I89582e2f868732e9a7a08a7a24f858b9130d56bc

openbmc/phosphor-logging,openbmc/phosphor-logging,openbmc/phosphor-logging,openbmc/phosphor-logging