LU-1417 lov: device type finalized twice

LU-1417 lov: device type finalized twice

lov_exit and osc_exit explicitly called lu_device_type_fini() right
before calling class_unregister_type().

However class_unregister_type() will call lu_device_type_fini() too,
which means lov_device_type and osc_device_type will be finalized
twice.

This can be fixed by removing lu_device_type_fini() calls from
lov_exit and osc_exit.

Signed-off-by: Liang Zhen <liang@whamcloud.com>
Change-Id: I12dea692f4d2bdd75bb1640b71c6dcc392b94478
Reviewed-on: http://review.whamcloud.com/2823
Tested-by: Hudson
Reviewed-by: Fan Yong <yong.fan@whamcloud.com>
Reviewed-by: Jinshan Xiong <jinshan.xiong@whamcloud.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>