x86/apic: Always define nox2apic and define it as initdata

x86/apic: Always define nox2apic and define it as initdata

The "nox2apic" variable can be defined as __initdata since it is
only used for bootstrap.  It can now unconditionally be defined
since it will later be freed.

At the same time, it is also better off as a bool.

Signed-off-by: David Rientjes <rientjes@google.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/alpine.DEB.2.02.1402042354380.7839@chino.kir.corp.google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>