It's not valid to set the TPWMTHRS in a "klippy:connect" event handler
because the TMCVirtualPinHelper and TMCCommandHelper classes were
expecting that field to be set during the config reading phase.
Revert "tmc: Fix typo preventing stealthchop threshold from being set"
This reverts commit 7d76067ff9.
Revert "tmc: Query the stepper step_distance from the stepper object"
This reverts commit 67b2852249.
Signed-off-by: Kevin O'Connor <kevin@koconnor.net>