nVMX: Extend EPT cap MSR test to allow 5-level EPT

Modify the EMSR_IA32_VMX_EPT_VPID_CAP test to mark the 5-level EPT cap
bit as allowed-1. KVM is in the process of gaining support for 5-level
nested EPT[*].

[*] https://lkml.kernel.org/r/20200206220836.22743-1-sean.j.christopherson@intel.com



Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200207174244.6590-5-sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>