soc/rockchip: Get rid of device_t

Use of device_t has been abandoned in ramstage.

Change-Id: Idf47ea3b29c3fab7256d7a6722c7978594001d8d
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/26535
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
diff --git a/src/soc/rockchip/rk3399/display.c b/src/soc/rockchip/rk3399/display.c
index f27d78e..43b9dab 100644
--- a/src/soc/rockchip/rk3399/display.c
+++ b/src/soc/rockchip/rk3399/display.c
@@ -48,7 +48,7 @@
 	printk(BIOS_WARNING, "Retrying EDP initialization.\n");
 }
 
-void rk_display_init(device_t dev)
+void rk_display_init(struct device *dev)
 {
 	struct edid edid;
 	struct soc_rockchip_rk3399_config *conf = dev->chip_info;