LU-13783 libcfs: use lsmcontext in security_release_secctx

LU-13783 libcfs: use lsmcontext in security_release_secctx

Kernel linux-hwe-5.8 (5.8.0-22.23~20.04.1) introduces
struct lsmcontext and uses it in security_release_secctx(),
which reduces the argruments from 2 to 1.

Change-Id: I37e185493001d335b40ea0a6102db593cb18beb3
Signed-off-by: Jian Yu <yujian@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/43284
Reviewed-by: Sebastien Buisson <sbuisson@ddn.com>
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>