Mark hypervisor memory region as unusable in its e820 table to avoid
being overlapped by e820_alloc_memory(). As it is already filtered out
in hypervisor e820 table, there is no longer need to filter it out in
service VM e820.
Tracked-On: #8738
Signed-off-by: Jiaqing Zhao <jiaqing.zhao@linux.intel.com>
Reviewed-by: Fei Li <fei1.li@intel.com>