vrend: remove obsolete state flag

BGRA emulation is always enabled, and this state flag is no longer used
for the past several months.

Signed-off-by: Ryan Neph <ryanneph@google.com>
Reviewed-by: Gert Wollny <gert.wollny@collabora.com>
Part-of: <https://gitlab.freedesktop.org/virgl/virglrenderer/-/merge_requests/725>

src/vrend_renderer.c

@@ -355,8 +355,6 @@ struct global_renderer_state {
    uint32_t stop_sync_thread : 1;
    /* async fence callback */
    bool use_async_fence_cb : 1;
-   /* Needed on GLES to inject a TCS */
-   uint32_t bgra_srgb_emulation_loaded : 1;
 
 #ifdef HAVE_EPOXY_EGL_H
    uint32_t use_egl_fence : 1;