q35: replace DEFINE_PROP_HEX32() with DEFINE_PROP_UINT32() and some fixups

Replace DEFINE_PROP_HEX32() with DEFINE_PROP_UINT32() in file
hw/i386/intel_iommu.c to port the patch for Intel_iommu device
model from Knuto to the latest version of QEMU.
To compile correctly, comment the unused variable and function.
Modify some comments.

Signed-off-by: Le Tan <tamlokveer@gmail.com>
acpi: add DMAR table to ACPI tables

If Type of TYPE_INTEL_IOMMU_DEVICE exists, add DMAR table to ACPI RSDT
table. For now the DMAR table indicates that there is only one hardware
unit without INTR_REMAP capability on the platform.

Signed-off-by: Le Tan <tamlokveer@gmail.com>