vt-d: Do dpci eoi outside of irq_lock.

vt-d: Do dpci eoi outside of irq_lock.

Deadlock may occur if do hvm_dpci_eoi() inside of irq_lock on MP
platform. For example, there are two physical cpus. If interrupt is
injected on cpu0, but vcpu is migrated to cpu1 and it does eoi inside
of irq_lock, then IPI will be issued to cpu0. At the same time, cpu0
may have disabled irq and is acquiring the same irq_lock. In addition,
current code cannot guarantee do hvm_dpci_eoi() inside of irq_lock
when timeout. This patch does hvm_dpci_eoi() outside of irq_lock, and
solves above problems.

Signed-off-by: Xiaohui Xin <xiaohui.xin@intel.com>
Signed-off-by: Weidong Han <weidong.han@intel.com>
Signed-off-by: Keir Fraser <keir@xensource.com>