nsh/script: remove double close for output fd

the output fd had been closed in nsh_closeifnotclosed, so
remove double close.

Signed-off-by: dongjiuzhu1 <dongjiuzhu1@xiaomi.com>

nshlib/nsh_script.c

@@ -74,7 +74,6 @@ static int nsh_script_redirect(FAR struct nsh_vtbl_s *vtbl,
       if (fd > 0)
         {
           nsh_undirect(vtbl, save);
-          close(fd);
         }
     }