LU-11658 lov: cl_cache could miss initialize

LU-11658 lov: cl_cache could miss initialize

The cl_cache may be missed initialize when we mount
a client with deactivate osc and then active it.

Signed-off-by: Yang Sheng <ys@whamcloud.com>
Change-Id: I92cd44375d70624fb55ef7a0218e7178211a8687
Reviewed-on: https://review.whamcloud.com/33650
Tested-by: Jenkins
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Patrick Farrell <paf@cray.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>