riscv and power8: Convert printk/while(1) to die

Change-Id: I277cc9ae22cd33f2cd9ded808960349d09e8670d
Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Reviewed-on: https://review.coreboot.org/16984
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

src/mainboard/emulation/qemu-riscv/mainboard.c

@@ -21,8 +21,7 @@ static void mainboard_enable(device_t dev)
 {
 
 	if (!dev) {
-		printk(BIOS_EMERG, "No dev0; die\n");
-		while (1);
+		die("No dev0; die\n");
 	}
 
 	ram_resource(dev, 0, 2048, 32768);