x86 VISWS: build fix

the 'reboot_force' flag is a notion that non-PC subarchitectures do
not have.

also, unify the X86_BIOS_REBOOT option between 32-bit and 64-bit
and get rid of a few unnecessary Kconfig and Makefile complications
that way.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

include/asm-x86/proto.h

@@ -20,7 +20,11 @@ extern void syscall32_cpu_init(void);
 
 extern void check_efer(void);
 
+#ifdef CONFIG_X86_BIOS_REBOOT
 extern int reboot_force;
+#else
+static const int reboot_force = 0;
+#endif
 
 long do_arch_prctl(struct task_struct *task, int code, unsigned long addr);