AMD and GFXUMA: move setup_uma_memory() to northbridge

UMA region can be determined at any time after the amount
of RAM is known and before the uma_resource() call.

Change-Id: I2a0bf2d3cad55ee70e889c88846f962b7faa0c7e
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: http://review.coreboot.org/1379
Reviewed-by: Zheng Bao <zheng.bao@amd.com>
Tested-by: build bot (Jenkins)
Reviewed-by: Anton Kochkov <anton.kochkov@gmail.com>

src/mainboard/amd/south_station/mainboard.c

@@ -79,8 +79,6 @@ static void southstation_led_init(void)
 static void southstation_enable(device_t dev)
 {
 	printk(BIOS_INFO, "Mainboard " CONFIG_MAINBOARD_PART_NUMBER " Enable.\n");
-	setup_uma_memory();
-
 	southstation_led_init();
 }