[HVM] Fix timer interrupt delivery on x64 Vista.

[HVM] Fix timer interrupt delivery on x64 Vista.

x64 SMP Vista HVM guest uses HPET as the main system timer, and it
uses physical destination mode with broadcast to deliver the interrupts
generated by HPET. In current code, timer interrupts are injected only
to VCPU0 in vioapic.c, but this doesn't satisfy x64 SMP Vista -- when
it boots, it complains "a clock interrupt was not received on a
secondary processor within the allocated time interval" with Bug Check
0x101.

Signed-off-by: Dexuan Cui <dexuan.cui@intel.com>