Fix last change of 'delete-file'

Fix last change of 'delete-file'

* src/fileio.c (Fdelete_file_internal): Expand file name here, as
all primitives must.
(internal_delete_file): Adjust to the fact that Fdelete_file was
renamed.

* lisp/files.el (delete-file): Don't expand-file-name here, as
the called primitives already do.  Fix typo in doc string.