sysrq: Restore original console_loglevel when sysrq disabled

BugLink: https://bugs.launchpad.net/bugs/1868628

commit 075e1a0c upstream.

The sysrq header line is printed with an increased loglevel
to provide users some positive feedback.

The original loglevel is not restored when the sysrq operation
is disabled. This bug was introduced in 2.6.12 (pre-git-history)
by the commit ("Allow admin to enable only some of the Magic-Sysrq
functions").
Signed-off-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Tommi Rantala <tommi.t.rantala@nokia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>
Signed-off-by: Kelsey Skunberg <kelsey.skunberg@canonical.com>

drivers/tty/sysrq.c

@@ -556,6 +556,7 @@ void __handle_sysrq(int key, bool check_mask)
 			op_p->handler(key);
 		} else {
 			pr_cont("This sysrq operation is disabled.\n");
+			console_loglevel = orig_log_level;
 		}
 	} else {
 		pr_cont("HELP : ");