[opentitantool] Fix warnings
[opentitantool] Fix warnings

TODO: Eliminate these macro definitions in favor of those supplied by
the `anyhow` crate.

Signed-off-by: Chris Frantz <d3397dc265da044816f611610217f391e4e7ef39@google.com>

lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan