init: mark console_on_rootfs as __init

This helper is only used for the early init code.
Signed-off-by: Christoph Hellwig <hch@lst.de>

init/main.c

@@ -1458,7 +1458,7 @@ static int __ref kernel_init(void *unused)
 }
 
 /* Open /dev/console, for stdin/stdout/stderr, this should never fail */
-void console_on_rootfs(void)
+void __init console_on_rootfs(void)
 {
 	struct file *file = filp_open("/dev/console", O_RDWR, 0);