KVM: VMX: Call vmx_get_cpl() directly in handle_dr()

Use vmx_get_cpl() instead of bouncing through kvm_x86_ops.get_cpl() when
performing a CPL check on MOV DR accesses.  This avoids a RETPOLINE (when
enabled), and more importantly removes a vendor reference to kvm_x86_ops
and helps pave the way for unexporting kvm_x86_ops.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220128005208.4008533-7-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/vmx/vmx.c

@@ -5184,7 +5184,7 @@ static int handle_dr(struct kvm_vcpu *vcpu)
 	if (!kvm_require_dr(vcpu, dr))
 		return 1;
 
-	if (kvm_x86_ops.get_cpl(vcpu) > 0)
+	if (vmx_get_cpl(vcpu) > 0)
 		goto out;
 
 	dr7 = vmcs_readl(GUEST_DR7);