vvmx: fix ept_sync() for nested p2m

vvmx: fix ept_sync() for nested p2m

If ept_sync_domain() is called for np2m, the following happens:

    1. *np2m*::ept_data::invalidate cpumask is updated
    2. IPIs are sent for CPUs in domain_dirty_cpumask forcing vmexits
    3. vmx_vmenter_helper() checks *hostp2m*::ept_data::invalidate
       and does nothing

Which is clearly a bug. Make ept_sync_domain() to update hostp2m's
invalidate mask in nested p2m case and make vmx_vmenter_helper() to
invalidate EPT translations for all EPTPs if nested virt is enabled.

Signed-off-by: Sergey Dyasli <sergey.dyasli@citrix.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Kevin Tian <kevin.tian@intel.com>