ceph: fix posix ACL hooks

The merge of commit 7221fe4c ("ceph: add acl for cephfs") raced with
upstream changes in the generic POSIX ACL code (eg commit 2aeccbe9
"fs: add generic xattr_acl handlers" and others).

Some of the fallout was fixed in commit 4db658ea

 ("ceph: Fix up after
semantic merge conflict"), but it was incomplete: the set_acl
inode_operation wasn't getting set, and the prototype needed to be
adjusted a bit (it doesn't take a dentry anymore).

Signed-off-by: Sage Weil <sage@inktank.com>
Signed-off-by: Ilya Dryomov <ilya.dryomov@inktank.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>