devtmpfs: initify a bit

devtmpfs_mount() is only called from prepare_namespace() in
init/do_mounts.c, which is an __init function, so devtmpfs_mount() can
also be moved to .init.text.

Then the mount_dev static variable is only referenced from __init
functions (devtmpfs_mount and its initializer function mount_param).
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Link: https://lore.kernel.org/r/20200115184154.3492-5-linux@rasmusvillemoes.dkSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/base/devtmpfs.c

@@ -30,7 +30,7 @@
 
 static struct task_struct *thread;
 
-static int mount_dev = IS_ENABLED(CONFIG_DEVTMPFS_MOUNT);
+static int __initdata mount_dev = IS_ENABLED(CONFIG_DEVTMPFS_MOUNT);
 
 static DEFINE_SPINLOCK(req_lock);
 
@@ -355,7 +355,7 @@ static int handle_remove(const char *nodename, struct device *dev)
  * If configured, or requested by the commandline, devtmpfs will be
  * auto-mounted after the kernel mounted the root filesystem.
  */
-int devtmpfs_mount(void)
+int __init devtmpfs_mount(void)
 {
 	int err;