iommufd/viommu: Release the igroup lock on the vdevice_size error path

In the Linux kernel, the following vulnerability has been resolved: iommufd/viommu: Release the igroup lock on the vdevice_size error path iommufd_vdevice_alloc_ioctl() takes idev->igroup->lock, then validates the driver's vdevice_size against the core structure size with a WARN_ON_ONCE. On failure that guard jumps to out_put_idev, below out_unlock_igroup, so it skips the mutex_unlock(), leaving the igroup lock held and deadlocking the next vDEVICE operation on that group. Jump to out_unlock_igroup instead.