KVM: VMX: replace "fall through" with "return" to indicate different case

The second "/* fall through */" in rmode_exception() makes code harder to
read. Replace it with "return" to indicate they are different cases, only
the #DB and #BP check vcpu->guest_debug, while others don't care. And this
also improves the readability.
Suggested-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Message-Id: <1582080348-20827-1-git-send-email-linmiaohe@huawei.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/vmx/vmx.c

@@ -4626,10 +4626,8 @@ static bool rmode_exception(struct kvm_vcpu *vcpu, int vec)
 			return false;
 		/* fall through */
 	case DB_VECTOR:
-		if (vcpu->guest_debug &
-			(KVM_GUESTDBG_SINGLESTEP | KVM_GUESTDBG_USE_HW_BP))
-			return false;
-		/* fall through */
+		return !(vcpu->guest_debug &
+			(KVM_GUESTDBG_SINGLESTEP | KVM_GUESTDBG_USE_HW_BP));
 	case DE_VECTOR:
 	case OF_VECTOR:
 	case BR_VECTOR: