ARM: 9139/1: kprobes: fix arch_init_kprobes() prototype

With extra warnings enabled, gcc complains about this function
definition:

arch/arm/probes/kprobes/core.c: In function 'arch_init_kprobes':
arch/arm/probes/kprobes/core.c:465:12: warning: old-style function definition [-Wold-style-definition]
  465 | int __init arch_init_kprobes()

Link: https://lore.kernel.org/all/20201027093057.c685a14b386acacb3c449e3d@kernel.org/

Fixes: 24ba613c ("ARM kprobes: core code")
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>

arch/arm/probes/kprobes/core.c

@@ -439,7 +439,7 @@ static struct undef_hook kprobes_arm_break_hook = {
 
 #endif /* !CONFIG_THUMB2_KERNEL */
 
-int __init arch_init_kprobes()
+int __init arch_init_kprobes(void)
 {
 	arm_probes_decode_init();
 #ifdef CONFIG_THUMB2_KERNEL