frwu: do not set interlacing flags.

Our fate frwu sample is definitely not interlaced.
If someone has a interlaced frwu file, please contact us.

Without this change the field order patch would cause
incorrect interlacing information to be written when
using frwu input.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/frwu.c

@@ -66,8 +66,6 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *data_size,
 
     pic->pict_type = AV_PICTURE_TYPE_I;
     pic->key_frame = 1;
-    pic->interlaced_frame = 1;
-    pic->top_field_first = 1;
 
     for (field = 0; field < 2; field++) {
         int i;