Rename ENABLE_AUTO_BED_LEVELING

With the introduction of the #if ENABLED(…)

reads better than

Marlin/vector_3.cpp

@@ -19,7 +19,7 @@
 #include <math.h>
 #include "Marlin.h"
 
-#if ENABLED(ENABLE_AUTO_BED_LEVELING)
+#if ENABLED(AUTO_BED_LEVELING_FEATURE)
 #include "vector_3.h"
 
 vector_3::vector_3() : x(0), y(0), z(0) { }
@@ -134,5 +134,5 @@ void matrix_3x3::debug(const char title[]) {
   }
 }
 
-#endif // ENABLE_AUTO_BED_LEVELING
+#endif // AUTO_BED_LEVELING_FEATURE