There is no one calling imx_drm_crtc_id() and it is just a simple
wrapper of drm_crtc_index() without doing any thing fancy - the
drivers may call drm_crtc_index() directly.  So, let's remove the
wrapper.
Signed-off-by: Liu Ying <gnuiyl@gmail.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
 module_param(legacyfb_depth, int, 0444);
 #endif
 
-unsigned int imx_drm_crtc_id(struct imx_drm_crtc *crtc)
-{
-       return drm_crtc_index(crtc->crtc);
-}
-EXPORT_SYMBOL_GPL(imx_drm_crtc_id);
-
 static void imx_drm_driver_lastclose(struct drm_device *drm)
 {
        struct imx_drm_device *imxdrm = drm->dev_private;
 
 struct imx_drm_crtc;
 struct platform_device;
 
-unsigned int imx_drm_crtc_id(struct imx_drm_crtc *crtc);
-
 struct imx_crtc_state {
        struct drm_crtc_state                   base;
        u32                                     bus_format;