drivers/char: don't use module_init in non-modular ttyprintk.c

The TTY_PRINTK option is bool, and hence this code is either
present or absent.  It will never be modular, so using
module_init as an alias for __initcall is rather misleading.

Fix this up now, so that we can relocate module_init from
init.h into module.h in the future.  If we don't do this, we'd
have to add module.h to obviously non-modular code, and that
would be a worse thing.

Note that direct use of __initcall is discouraged, vs. one
of the priority categorized subgroups.  As __initcall gets
mapped onto device_initcall, our use of device_initcall
directly in this change means that the runtime impact is
zero -- it will remain at level 6 in initcall ordering.
Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/char/ttyprintk.c

@@ -216,4 +216,4 @@ static int __init ttyprintk_init(void)
 	ttyprintk_driver = NULL;
 	return ret;
 }
-module_init(ttyprintk_init);
+device_initcall(ttyprintk_init);