drivers/tty: make sysrq.c slightly more explicitly non-modular

The Kconfig currently controlling compilation of this code is:

config.debug:config MAGIC_SYSRQ
      bool "Magic SysRq key"

...meaning that it currently is not being built as a module by anyone.

Lets remove the traces of modularity we can so that when reading the
driver there is less doubt it is builtin-only.

Since module_init translates to device_initcall in the non-modular
case, the init ordering remains unchanged with this commit.

We don't delete the module.h include since other parts of the file are
using content from there.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/sysrq.c

@@ -1003,6 +1003,10 @@ static const struct kernel_param_ops param_ops_sysrq_reset_seq = {
 #define param_check_sysrq_reset_seq(name, p)	\
 	__param_check(name, p, unsigned short)
 
+/*
+ * not really modular, but the easiest way to keep compat with existing
+ * bootargs behaviour is to continue using module_param here.
+ */
 module_param_array_named(reset_seq, sysrq_reset_seq, sysrq_reset_seq,
 			 &sysrq_reset_seq_len, 0644);
 
@@ -1119,4 +1123,4 @@ static int __init sysrq_init(void)
 
 	return 0;
 }
-module_init(sysrq_init);
+device_initcall(sysrq_init);