y86/vmx: dump PIR and vIRR before ASSERT()

y86/vmx: dump PIR and vIRR before ASSERT()

Commit c7bdecae42 ("x86/apicv: fix RTC periodic timer and apicv issue") has
added a assertion that intack.vector is the highest priority vector. But
according to the osstest, the assertion failed sometimes. More discussion can
be found in the thread
(https://lists.xenproject.org/archives/html/xen-devel/2017-01/msg01019.html).

The assertion failure is hard to reproduce. In order to root cause issue, this
patch is to add logs to dump PIR and vIRR when failure takes place. It should
be reverted once the root cause is found.

Signed-off-by: Chao Gao <chao.gao@intel.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Kevin Tian <kevin.tian@intel.com>