d3d11va: fix a crash when we can't allocate the decoding texture

Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

modules/codec/avcodec/d3d11va.c

@@ -711,6 +711,7 @@ static int DxCreateDecoderSurfaces(vlc_va_t *va, int codec_id, const video_forma
     hr = ID3D11Device_CreateTexture2D( (ID3D11Device*) dx_sys->d3ddev, &texDesc, NULL, &p_texture );
     if (FAILED(hr)) {
         msg_Err(va, "CreateTexture2D %d failed. (hr=0x%0lx)", dx_sys->surface_count, hr);
+        dx_sys->surface_count = 0;
         return VLC_EGENERIC;
     }