KVM: x86: don't take kvm->irq_lock when creating IRQCHIP

I don't see any reason any more for this lock, seemed to be used to protect
removal of kvm->arch.vpic / kvm->arch.vioapic when already partially
inititalized, now access is properly protected using kvm->arch.irqchip_mode
and this shouldn't be necessary anymore.
Signed-off-by: NDavid Hildenbrand <david@redhat.com>
Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com>

arch/x86/kvm/x86.c

@@ -4028,10 +4028,8 @@ long kvm_arch_vm_ioctl(struct file *filp,
 			/* Pairs with smp_rmb() when reading irqchip_mode */
 			smp_wmb();
 			mutex_lock(&kvm->slots_lock);
-			mutex_lock(&kvm->irq_lock);
 			kvm_ioapic_destroy(kvm);
 			kvm_pic_destroy(kvm);
-			mutex_unlock(&kvm->irq_lock);
 			mutex_unlock(&kvm->slots_lock);
 			goto create_irqchip_unlock;
 		}