nVMX: Test vmentry of unrestricted (PG=0/PE=1) nested guest

According to section "UNRESTRICTED GUESTS" in SDM vol 3c, if the
"unrestricted guest" secondary VM-execution control is set, guests can run
in unpaged protected mode or in real mode. This patch tests vmentry of an
unrestricted guest in unpaged protected mode.

Signed-off-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
Message-Id: <20200921081027.23047-4-krish.sadhukhan@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>