x86, intr-remap: fix eoi for interrupt remapping without x2apic

To simplify level irq migration in the presence of interrupt-remapping,
Suresh used a virtual vector (io-apic pin number) to eliminate io-apic
RTE modification. Level triggered interrupt will appear as an edge to
the local apic cpu but still as level to the IO-APIC. So in addition to
do the local apic EOI, it still needs to do IO-APIC directed EOI to clear
the remote IRR bit in the IO-APIC RTE. Pls refer to Suresh's patch for
more details (commit 0280f7c4).

Now interrupt remapping is decoupled from x2apic, it also needs to do the
directed EOI for apic. Otherwise, apic interrupts won't work correctly.

Signed-off-by: Weidong Han <weidong.han@intel.com>
Cc: iommu@lists.linux-foundation.org
Cc: Weidong Han <weidong.han@intel.com>
Cc: suresh.b.siddha@intel.com
Cc: dwmw2@infradead.org
Cc: allen.m.kay@intel.com
LKML-Reference: <1239355037-22856-1-git-send-email-weidong.han@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>