KVM: x86: Drop superfluous "has assigned device" check in kvm_pi_update_irte()

KVM: x86: Drop superfluous "has assigned device" check in kvm_pi_update_irte()

Don't bother checking if the VM has an assigned device when updating
IRTE entries.  kvm_arch_irq_bypass_add_producer() explicitly increments
the assigned device count, kvm_arch_irq_bypass_del_producer() explicitly
decrements the count before invoking kvm_pi_update_irte(), and
kvm_irq_routing_update() only updates IRTE entries if there's an active
IRQ bypass producer.

Link: https://lore.kernel.org/r/20250611224604.313496-51-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>