Add support for CoreYZ to planner.buffer_line

Marlin/planner.cpp

       enable_z();
     }
     if (block->steps[Y_AXIS]) enable_y();
+  #elif ENABLED(COREYZ)
+    if (block->steps[B_AXIS] || block->steps[C_AXIS]) {
+      enable_y();
+      enable_z();
+    }
+    if (block->steps[X_AXIS]) enable_x();
   #else
     if (block->steps[X_AXIS]) enable_x();
     if (block->steps[Y_AXIS]) enable_y();