XXXX don't fail device detach when it's physically removed

*** 16,28 ****
   * fields enclosed by brackets "[]" replaced with your own identifying
   * information: Portions Copyright [yyyy] [name of copyright owner]
   *
   * CDDL HEADER END
   */
  /*
   * Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved.
!  * Copyright 2012 Nexenta Systems, Inc. All rights reserved.
   * Copyright 2012 Garrett D'Amore <garrett@damore.org>.  All rights reserved.
   * Copyright (c) 2013, Joyent, Inc. All rights reserved.
   * Copyright (c) 2016 by Delphix. All rights reserved.
   */
  
--- 16,29 ----
   * fields enclosed by brackets "[]" replaced with your own identifying
   * information: Portions Copyright [yyyy] [name of copyright owner]
   *
   * CDDL HEADER END
   */
+ 
  /*
   * Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved.
!  * Copyright 2018 Nexenta Systems, Inc.
   * Copyright 2012 Garrett D'Amore <garrett@damore.org>.  All rights reserved.
   * Copyright (c) 2013, Joyent, Inc. All rights reserved.
   * Copyright (c) 2016 by Delphix. All rights reserved.
   */
  
*** 1358,1369 ****
          int             rv;
  
          ASSERT(DEVI_BUSY_OWNED(ddi_get_parent(dip)));
          ASSERT(i_ddi_node_state(dip) == DS_ATTACHED);
  
!         /* check references */
!         if (DEVI(dip)->devi_ref)
                  return (DDI_FAILURE);
  
          NDI_CONFIG_DEBUG((CE_CONT, "detach_node: 0x%p(%s%d)\n",
              (void *)dip, ddi_driver_name(dip), ddi_get_instance(dip)));
  
--- 1359,1370 ----
          int             rv;
  
          ASSERT(DEVI_BUSY_OWNED(ddi_get_parent(dip)));
          ASSERT(i_ddi_node_state(dip) == DS_ATTACHED);
  
!         /* Check references */
!         if (DEVI(dip)->devi_ref != 0 && !DEVI(dip)->devi_gone)
                  return (DDI_FAILURE);
  
          NDI_CONFIG_DEBUG((CE_CONT, "detach_node: 0x%p(%s%d)\n",
              (void *)dip, ddi_driver_name(dip), ddi_get_instance(dip)));
  
*** 3819,3830 ****
   * with argument "ioc@xxxxxxx,yyyyyyy:port=1". After configuring
   * the ioc, look for minor node dhcp. If not found, pass ":dhcp"
   * to ioc's bus_config entry point.
   */
  int
! resolve_pathname(char *pathname,
!         dev_info_t **dipp, dev_t *devtp, int *spectypep)
  {
          int                     error;
          dev_info_t              *parent, *child;
          struct pathname         pn;
          char                    *component, *config_name;
--- 3820,3831 ----
   * with argument "ioc@xxxxxxx,yyyyyyy:port=1". After configuring
   * the ioc, look for minor node dhcp. If not found, pass ":dhcp"
   * to ioc's bus_config entry point.
   */
  int
! resolve_pathname(char *pathname, dev_info_t **dipp, dev_t *devtp,
!     int *spectypep)
  {
          int                     error;
          dev_info_t              *parent, *child;
          struct pathname         pn;
          char                    *component, *config_name;