auxdisplay: charlcd: no need to call charlcd_gotoxy() if nothing changes

If the line extends beyond the width to the screen, nothing changes. The
existing code will call charlcd_gotoxy every time for this case.

Signed-off-by: Sean Young <sean@mess.org>
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>