MRP-2059 osd: add osd_ost_fini in osd_obj_map_init

In case of ENOSPC in osd_mdt_init->simple_mkdir("REMOTE_PARENT_DIR")
missed dput(for "O") causes kernel panic with msg:
BUG: Dentry ffff88005d6b3e40{i=b2,n=O} still in use (1)

Change-Id: Ibd5391e781e19efe48e9a9700ee4565b46c2f0b5
Signed-off-by: Sergey Cheremencev <sergey.cheremencev@seagate.com>
Reviewed-on: http://es-gerrit.xyus.xyratex.com:8080/4431
Tested-by: Jenkins
Reviewed-by: Alexander Zarochentsev <alexander_zarochentsev@xyratex.com>
Reviewed-by: Rahul Deshmukh <rahul_deshmukh@xyratex.com>
Tested-by: Elena Gryaznova <elena.gryaznova@seagate.com>
Reviewed-by: Vitaly Fertman <vitaly.fertman@seagate.com>