Input('vm0_gpa') should be validated when handling
hypercall 'HC_VM_SET_MEMMAP to create EPT for UOS
in 'hcall_set_vm_memmap()' function.
at least 'hpa' range (from 'vm0_gpa') can't overlap
hypervisor memory region.
Signed-off-by: Yonghua Huang <yonghua.huang@intel.com>