drm/fb-helper: add DRM_FB_HELPER_DEFAULT_OPS for fb_ops

The define DRM_FB_HELPER_DEFAULT_OPS provides the drm_fb_helper default
implementations for functions in struct fb_ops. A drm driver can use it
like:

    static struct fb_ops drm_fbdev_cma_ops = {
        .owner          = THIS_MODULE,
        DRM_FB_HELPER_DEFAULT_OPS,
        /* driver specific implementations */
    };

Suggested-by: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Stefan Christ <contact@stefanchrist.eu>
Reviewed-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1475182136-15191-2-git-send-email-contact@stefanchrist.eu

include/drm/drm_fb_helper.h

@@ -217,6 +217,19 @@ struct drm_fb_helper {
 	bool delayed_hotplug;
 };
 
+/**
+ * @DRM_FB_HELPER_DEFAULT_OPS:
+ *
+ * Helper define to register default implementations of drm_fb_helper
+ * functions. To be used in struct fb_ops of drm drivers.
+ */
+#define DRM_FB_HELPER_DEFAULT_OPS \
+	.fb_check_var	= drm_fb_helper_check_var, \
+	.fb_set_par	= drm_fb_helper_set_par, \
+	.fb_setcmap	= drm_fb_helper_setcmap, \
+	.fb_blank	= drm_fb_helper_blank, \
+	.fb_pan_display	= drm_fb_helper_pan_display
+
 #ifdef CONFIG_DRM_FBDEV_EMULATION
 void drm_fb_helper_prepare(struct drm_device *dev, struct drm_fb_helper *helper,
 			   const struct drm_fb_helper_funcs *funcs);