avcodec: pass coded dimensions to hardware decoder

Regression from b71c85b3.

modules/codec/avcodec/video.c

@@ -907,7 +907,7 @@ static int ffmpeg_va_GetFrameBuf( struct AVCodecContext *p_context, AVFrame *p_f
     /* hwaccel_context is not present in old ffmpeg version */
     if( vlc_va_Setup( p_va,
                 &p_context->hwaccel_context, &p_dec->fmt_out.video.i_chroma,
-                p_context->width, p_context->height ) )
+                p_context->coded_width, p_context->coded_height ) )
     {
         msg_Err( p_dec, "vlc_va_Setup failed" );
         return -1;