drm/exynos: Staticize exynos_dpi_of_find_panel_node

exynos_dpi_of_find_panel_node is local to this file.
Signed-off-by: NSachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Inki Dae <inki.dae>

drivers/gpu/drm/exynos/exynos_drm_dpi.c

@@ -235,7 +235,7 @@ enum {
 	FIMD_PORT_WRB,
 };
 
-struct device_node *exynos_dpi_of_find_panel_node(struct device *dev)
+static struct device_node *exynos_dpi_of_find_panel_node(struct device *dev)
 {
 	struct device_node *np, *ep;