[IA64] Fix registered interrupt check

Fix the problem that interrupts are not initialized correctly at PCI
hotplug or driver reloading time.

By vector domain change, the iosapic_rte_info structure was changed to
be on the iosapic_intr_info[irq].rtes list even after the interrupts
are unregistered. So iosapic_intr_info[irq].rtes list must not be
checked to see if there are registered interrupts (RTEs) on the
irq. We must check iosapic_intr_info[irq].count counter instead.

Signed-off-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>