fixing internal parameter name from previous commit

Author: bigcat88

pillow_heif/as_opener.py

@@ -108,12 +108,12 @@ def _init_from_heif_file(self, img_index: int) -> None:
 
 
 def _save(im, fp, _filename):
-    heif_file = HeifFile().add_from_pillow(im, load_one=True, thumbs_no_data=True)
+    heif_file = HeifFile().add_from_pillow(im, load_one=True, for_encoding=True)
     heif_file.save(fp, save_all=False, **im.encoderinfo)
 
 
 def _save_all(im, fp, _filename):
-    heif_file = HeifFile().add_from_pillow(im, ignore_primary=False, thumbs_no_data=True)
+    heif_file = HeifFile().add_from_pillow(im, ignore_primary=False, for_encoding=True)
     heif_file.save(fp, save_all=True, **im.encoderinfo)