staging: next: configfs: fix release link

The functions link_destroy and link_release are both deleting list items.
link_release, however, does not check whether a certain link has already
been deleted from the list by function link_destroy. By fixing this
this patch prevents a kernel crash when removing the configuration
directory of a link that already has been destroyed.

Signed-off-by: Christian Gromm <christian.gromm@microchip.com>
Link: https://lore.kernel.org/r/1579793906-5054-7-git-send-email-christian.gromm@microchip.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>