Revert "kvm: detect assigned device via irqbypass manager"

Now that KVM explicitly tracks the number of possible bypass IRQs, and
doesn't conflate IRQ bypass with host MMIO access, stop bumping the
assigned device count when adding an IRQ bypass producer.

This reverts commit 2edd9cb79fb31b0907c6e0cdce2824780cf9b153.

Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Sean Christopherson <[e-mail]>

arch/x86/kvm/irq.c

···
 	struct kvm *kvm = irqfd->kvm;
 	int ret = 0;
 
-	kvm_arch_start_assignment(irqfd->kvm);
-
 	spin_lock_irq(&kvm->irqfds.lock);
 	irqfd->producer = prod;
 
···
 
 	if (irqfd->irq_entry.type == KVM_IRQ_ROUTING_MSI) {
 		ret = kvm_pi_update_irte(irqfd, &irqfd->irq_entry);
-		if (ret) {
+		if (ret)
 			kvm->arch.nr_possible_bypass_irqs--;
-			kvm_arch_end_assignment(irqfd->kvm);
-		}
 	}
 	spin_unlock_irq(&kvm->irqfds.lock);
 
···
 	kvm->arch.nr_possible_bypass_irqs--;
 
 	spin_unlock_irq(&kvm->irqfds.lock);
-
-
-	kvm_arch_end_assignment(irqfd->kvm);
 }
 
 void kvm_arch_update_irqfd_routing(struct kvm_kernel_irqfd *irqfd,