drm: omapdrm: Make fbdev emulation optional

Don't compile the fbdev emulation code when fbdev emulation support is
disabled.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
diff --git a/drivers/gpu/drm/omapdrm/omap_drv.h b/drivers/gpu/drm/omapdrm/omap_drv.h
index 130fca7..289d9b0 100644
--- a/drivers/gpu/drm/omapdrm/omap_drv.h
+++ b/drivers/gpu/drm/omapdrm/omap_drv.h
@@ -138,8 +138,18 @@
 void omap_drm_irq_uninstall(struct drm_device *dev);
 int omap_drm_irq_install(struct drm_device *dev);
 
+#ifdef CONFIG_DRM_FBDEV_EMULATION
 struct drm_fb_helper *omap_fbdev_init(struct drm_device *dev);
 void omap_fbdev_free(struct drm_device *dev);
+#else
+static inline struct drm_fb_helper *omap_fbdev_init(struct drm_device *dev)
+{
+	return NULL;
+}
+static inline void omap_fbdev_free(struct drm_device *dev)
+{
+}
+#endif
 
 struct omap_video_timings *omap_crtc_timings(struct drm_crtc *crtc);
 enum omap_channel omap_crtc_channel(struct drm_crtc *crtc);