Fix teletext page aspect ratio

It was broken by 29a4015294, which should only have modified text "subpictures"
Closes #13050
Tested-by: Julian Scheel <julian@jusst.de>

(cherry picked from commit 47f215557953d40ed0d0b38a7834917e9117cc2b)
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

modules/codec/zvbi.c

@@ -522,6 +522,7 @@ static subpicture_t *Subpicture( decoder_t *p_dec, video_format_t *p_fmt,
         fmt.i_width = fmt.i_visible_width = i_columns * 12;
         fmt.i_height = fmt.i_visible_height = i_rows * 10;
         fmt.i_bits_per_pixel = 32;
+        fmt.i_sar_num = fmt.i_sar_den = 0; /* let the vout set the correct AR */
     }
     fmt.i_x_offset = fmt.i_y_offset = 0;