mb/amd: Get rid of device_t

Use of device_t has been abandoned in ramstage.

Change-Id: I01270248bddf07df4c959f0c632e722728d0cd03
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/26072
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

src/mainboard/amd/south_station/mainboard.c

@@ -49,7 +49,7 @@ static void southstation_led_init(void)
 /**********************************************
  * Enable the dedicated functions of the board.
  **********************************************/
-static void mainboard_enable(device_t dev)
+static void mainboard_enable(struct device *dev)
 {
 	printk(BIOS_INFO, "Mainboard " CONFIG_MAINBOARD_PART_NUMBER " Enable.\n");
 	southstation_led_init();