vim-patch:9.1.1601: Patch v8.1.0425 was wrong

Problem:  Patch v8.1.0425 was wrong
Solution: Revert that patch (Hirohito Higashi)

This is because the root cause was fixed in 8.1.0786 and a regression
occurred elsewhere.

related: vim/vim#3455
related: vim/vim#3830
fixes: vim/vim#11558
closes: vim/vim#17899

6abe5e4904

Co-authored-by: Hirohito Higashi <h.east.727@gmail.com>
(cherry picked from commit 7230296bdb)

src/nvim/buffer.c

@@ -1728,9 +1728,6 @@ void enter_buffer(buf_T *buf)
   // mark cursor position as being invalid
   curwin->w_valid = 0;
 
-  buflist_setfpos(curbuf, curwin, curbuf->b_last_cursor.mark.lnum,
-                  curbuf->b_last_cursor.mark.col, true);
-
   // Make sure the buffer is loaded.
   if (curbuf->b_ml.ml_mfp == NULL) {    // need to load the file
     // If there is no filetype, allow for detecting one.  Esp. useful for