This is to do the clean-up of IOAPIC mmio-access. Use the same API to
access the IOAPIC register. At the same time it also helps to avoid the
optimization in direct access mode.(The volatile is already added in
mmio_read_long/mmio_write_long)
V1->V2: Follow Fengwei's suggestion to use the mmio_read/write_long
Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Reviewed-by: Yin Fengwei <fengwei.yin@intel.com>