cdgraphics: fix incorrect vertical offset mask in cdg_scroll()

The vertical offset mask 0x07 is suspicious.

    v_off = FFMIN(data[2] & 0x07, CDG_BORDER_HEIGHT - 1);

Note that v_off is up to 11 (CDG_BORDER_HEIGHT - 1), the correct mask
should be 0x0F.
Signed-off-by: Xi Wang <xi.wang@gmail.com>
Signed-off-by: Anton Khirnov <anton@khirnov.net>

libavcodec/cdgraphics.c

@@ -218,7 +218,7 @@ static void cdg_scroll(CDGraphicsContext *cc, uint8_t *data,
     vscmd = (data[2] & 0x30) >> 4;
 
     h_off =  FFMIN(data[1] & 0x07, CDG_BORDER_WIDTH  - 1);
-    v_off =  FFMIN(data[2] & 0x07, CDG_BORDER_HEIGHT - 1);
+    v_off =  FFMIN(data[2] & 0x0F, CDG_BORDER_HEIGHT - 1);
 
     /// find the difference and save the offset for cdg_tile_block usage
     hinc = h_off - cc->hscroll;