KVM: VMX: Use ept_caps_to_lpage_level() in hardware_setup()

Using ept_caps_to_lpage_level is simpler.

Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Message-Id: <20211124122055.64424-9-jiangshanlai@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>