Fix ExtUI base methods

Marlin/src/lcd/extui/ui_api.cpp

 
   void setAxisSteps_per_mm(const float value, const extruder_t extruder) {
     UNUSED_E(extruder);
-    planner.settings.axis_steps_per_mm[E_AXIS_N(axis - E0)] = value;
+    planner.settings.axis_steps_per_mm[E_AXIS_N(extruder - E0)] = value;
   }
 
   feedRate_t getAxisMaxFeedrate_mm_s(const axis_t axis) {
 
   feedRate_t getAxisMaxFeedrate_mm_s(const extruder_t extruder) {
     UNUSED_E(extruder);
-    return planner.settings.max_feedrate_mm_s[E_AXIS_N(axis - E0)];
+    return planner.settings.max_feedrate_mm_s[E_AXIS_N(extruder - E0)];
   }
 
   void setAxisMaxFeedrate_mm_s(const feedRate_t value, const axis_t axis) {