drm/imx: Use drm_mode_duplicate()

Replace the hand rolled drm_mode_duplicate() with the
real thing.

@is_dup@
@@
drm_mode_duplicate(...)
{ ... }

@depends on !is_dup@
expression dev, oldmode;
identifier newmode;
@@
- newmode = drm_mode_create(dev);
+ newmode = drm_mode_duplicate(dev, oldmode);
  ...
- drm_mode_copy(newmode, oldmode);

Cc: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220218100403.7028-10-ville.syrjala@linux.intel.comReviewed-by: Philipp Zabel <p.zabel@pengutronix.de>

drivers/gpu/drm/imx/imx-ldb.c

@@ -150,10 +150,9 @@ static int imx_ldb_connector_get_modes(struct drm_connector *connector)
 	if (imx_ldb_ch->mode_valid) {
 		struct drm_display_mode *mode;
 
-		mode = drm_mode_create(connector->dev);
+		mode = drm_mode_duplicate(connector->dev, &imx_ldb_ch->mode);
 		if (!mode)
 			return -EINVAL;
-		drm_mode_copy(mode, &imx_ldb_ch->mode);
 		mode->type |= DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED;
 		drm_mode_probed_add(connector, mode);
 		num_modes++;