x86/io_apic: Move and reenable irq only when CONFIG_GENERIC_PENDING_IRQ=y

x86/io_apic: Move and reenable irq only when CONFIG_GENERIC_PENDING_IRQ=y

This patch removes dead code from certain .config variations.

When CONFIG_GENERIC_PENDING_IRQ=n irq move and reenable code is
never get executed, nor do_unmask_irq variable updates its init
value. Move the code under CONFIG_GENERIC_PENDING_IRQ macro.

Signed-off-by: Alexander Gordeev <agordeev@redhat.com>
Link: http://lkml.kernel.org/r/20120320141935.GA24806@dhcp-26-207.brq.redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>