sysrq: Allow magic SysRq key functions to be disabled through Kconfig

Turn the initial value of sysctl kernel.sysrq (SYSRQ_DEFAULT_ENABLE)
into a Kconfig variable.

Original version by Bastian Blank <waldi@debian.org>.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index b2f06f3..8b80f1b 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -190,7 +190,7 @@
 
 #ifdef CONFIG_MAGIC_SYSRQ
 /* Note: sysrq code uses it's own private copy */
-static int __sysrq_enabled = SYSRQ_DEFAULT_ENABLE;
+static int __sysrq_enabled = CONFIG_MAGIC_SYSRQ_DEFAULT_ENABLE;
 
 static int sysrq_sysctl_handler(ctl_table *table, int write,
 				void __user *buffer, size_t *lenp,