staging: unisys: visorbus: Fix memory leak

The name of a visor_device was never freed, which was allocated in
visorbus_configure.

It is expected that visorbus_device_destroy will not be called on the
same visor_device again, or this would be a double free.

Signed-off-by: Zachary Dremann <dremann@gmail.com>
Signed-off-by: David Kershner <david.kershner@unisys.com>
Reviewed-by: David Binder <david.binder@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>