Revert "LaTeX export: Fix interpretation of \nbsp"

This reverts commit e85508d5cfc3fd44d197134c6e5060847cda0f87.

lisp/org-latex.el

@@ -1731,7 +1731,6 @@ The conversion is made depending of STRING-BEFORE and STRING-AFTER."
    "\\medskip"
    "\\multicolumn"
    "\\multiput"
-   "\\nbsp"
    "\\newcommand"
    "\\newcounter"
    "\\newenvironment"