cavsdec: avoid possible crash with crafted input

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
(cherry picked from commit 9f06c1c61e876e930753da200bfe835817e30a53)
diff --git a/libavcodec/cavsdec.c b/libavcodec/cavsdec.c
index 8d30040..25b97bf 100644
--- a/libavcodec/cavsdec.c
+++ b/libavcodec/cavsdec.c
@@ -165,7 +165,7 @@
 
     /* get coded block pattern */
     int cbp= get_ue_golomb(&h->s.gb);
-    if(cbp > 63){
+    if(cbp > 63U){
         av_log(h->s.avctx, AV_LOG_ERROR, "illegal inter cbp\n");
         return -1;
     }
@@ -225,7 +225,7 @@
     /* get coded block pattern */
     if(h->pic_type == FF_I_TYPE)
         cbp_code = get_ue_golomb(gb);
-    if(cbp_code > 63){
+    if(cbp_code > 63U){
         av_log(h->s.avctx, AV_LOG_ERROR, "illegal intra cbp\n");
         return -1;
     }