hv: change several APIs to void type

Change these 6 APIs to void type:
  init_default_irqs
  interrupt_init
  early_init_lapic
  init_lapic
  init_iommu
  destroy_iommu_domain
It has checked the argument of destroy_iommu_domain in shutdown_vm,
then no need to check it again inside destroy_iommu_domain.

Signed-off-by: Mingqiang Chi <mingqiang.chi@intel.com>
Reviewed-by: Junjie Mao <junjie.mao@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>

hypervisor/boot/dmar_parse.c

@@ -322,6 +322,9 @@ int parse_dmar_table(void)
 	return 0;
 }
 
+/**
+ * @post return != NULL
+ */
 struct dmar_info *get_dmar_info(void)
 {
 	parse_dmar_table();