change arm constants in header to match EncoderLine #define in code

This should not make any difference unless there is something
buried somewhere that is doing calculations based on the old order

but not being sure how the dats is passed to the UI for calibration
this may be the case.

FluidNC/src/Maslow/Maslow.h

@@ -236,10 +236,10 @@ class Maslow_ {
     unsigned long holdTime  = 0;
 
     //variables to use as indexes into various arrays
-    const char tl = 0;
+    const char tl = 2;
     const char tr = 1;
-    const char bl = 2;
-    const char br = 3;
+    const char bl = 3;
+    const char br = 0;
 
     // per-arm arrays
     float zOffset[4];