x86: Remove unused variable disable_x2apic

setup_nox2apic() is writing 1 to disable_x2apic but no one is reading it.

Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
LKML-Reference: <1246554239.2242.27.camel@jaswinder.satnam>
Signed-off-by: Ingo Molnar <mingo@elte.hu>