[WIP] Fix Probe::offset_xy (#20290)

Co-authored-by: Jason Smith <jason.inet@gmail.com>

Marlin/src/module/probe.cpp

 xyz_pos_t Probe::offset; // Initialized by settings.load()
 
 #if HAS_PROBE_XY_OFFSET
-  const xy_pos_t &Probe::offset_xy = xy_pos_t(Probe::offset);
+  const xy_pos_t &Probe::offset_xy = Probe::offset;
 #endif
 
 #if ENABLED(Z_PROBE_SLED)