LU-1337 vfs: generic_permission has 2 args

LU-1337 vfs: generic_permission has 2 args

generic_permission has 2 args since kernel 3.1
(kernel commit 2830ba7f34ebb27c4e5b8b6ef408cd6d74860890).

Signed-off-by: Liu Xuezhao <xuezhao.liu@emc.com>
Change-Id: I1ee2d127af3dfdc3c24f1466d9e183918c3a652c
Reviewed-on: http://review.whamcloud.com/3397
Tested-by: Hudson
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Yang Sheng <ys@whamcloud.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: James Simmons <uja.ornl@gmail.com>