Fixed DXVA_Slice_H264_Long::BitOffsetToSliceData value.

The 8 bits offset (nal unit type) should not be added, as the spec says:

"This bit offset is the offset within the RBSP data for the slice, relative
to the starting position of the slice_header() in the RBSP"

This fixes DXVA2 support for intel GPU.

Patch by Rafaël Carré (funman _AT_ videolan _DOT_ org).

Originally committed as revision 25538 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/dxva2_h264.c

@@ -194,7 +194,7 @@ static void fill_slice_long(AVCodecContext *avctx, DXVA_Slice_H264_Long *slice,
 
     slice->first_mb_in_slice     = (s->mb_y >> FIELD_OR_MBAFF_PICTURE) * s->mb_width + s->mb_x;
     slice->NumMbsForSlice        = 0; /* XXX it is set once we have all slices */
-    slice->BitOffsetToSliceData  = get_bits_count(&s->gb) + 8;
+    slice->BitOffsetToSliceData  = get_bits_count(&s->gb);
     slice->slice_type            = ff_h264_get_slice_type(h);
     if (h->slice_type_fixed)
         slice->slice_type += 5;