vc1: enable interlaced p fields again, they seem no longer to crash with out of array writes

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/vc1.c

@@ -987,8 +987,6 @@ int vc1_parse_frame_header_adv(VC1Context *v, GetBitContext* gb)
         break;
     case AV_PICTURE_TYPE_P:
         if (v->field_mode) {
-            av_log(v->s.avctx, AV_LOG_ERROR, "P Fields do not work currently\n");
-            return -1;
             v->numref = get_bits1(gb);
             if (!v->numref) {
                 v->reffield          = get_bits1(gb);