Update to Bugfix 2.0.x #16619

[ellensp]

Requirements

MOTHERBOARD BOARD_BIGTREE_SKR_V1_3
Home direction 1 for at least one axis.
enable SENSORLESS_HOMING
enable a TMC driver with SENSORLESS_HOMING

Description

This is a update to PR #16659
The current test is
if {X|Y|Z}HOME_DIR > 0 && {X|Y|Z}STALL_SENSITIVITY && !defined(USE{X|Y|Z}MAX_PLUG)
the idea being that if USE{X|Y|Z}MAX_PLUG is defined they also have endstops on real ZMAX_PLUG and not swap the pins.

But

Marlin will not let you home to 1 without setting USE_{X|Y|Z}MAX_PLUG. so this test always fails. The result is that now MIN and MAX never swap over. This is an issue for anyone who need to home to max using SENSORLESS_HOMING.

I have removed the MAX_PLUG part of the test and added a simple flag {X|Y|Z}_NO_SWAP to override pin swapping in obscure cases where it may be needed.

Benefits

MIN and MAX pin swap as needed and swapping can be disabled if required.

Related Issues

#16619
#16677

[thinkyhead]

Thanks for taking a crack at this. See #16723 for a more comprehensive solution. We have to treat boards with distinct DIAG pins differently from boards that map them to endstops. And for boards that don't have DIAG pins, you can choose where to plug them in so this is not an issue.