LU-11775 osc: check if opg is in lru list without locking

LU-11775 osc: check if opg is in lru list without locking

osc_lru_use is called for every page queued for io,
we can just check if the osc_page is in the lru list
without taking the cl_lru_list_lock and return if not
as a fast path.
Note we still need to do the check again after locking
as it could be removed from the lru list by another thread.

Signed-off-by: Li Dongyang <dongyangli@ddn.com>
Change-Id: I1587b6b5547ae5a7a8bfe32a78361bb888c85d5b
Reviewed-on: https://review.whamcloud.com/33860
Reviewed-by: Patrick Farrell <pfarrell@whamcloud.com>
Tested-by: Jenkins
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Alexey Lyashkov <c17817@cray.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>