ceph: noacl mount option is effectively ignored

For the old mount API, the module parameters parseing function will
be called in ceph_mount() and also just after the default posix acl
flag set, so we can control to enable/disable it via the mount option.

But for the new mount API, it will call the module parameters
parseing function before ceph_get_tree(), so the posix acl will always
be enabled.

Fixes: 82995cc6 ("libceph, rbd, ceph: convert to use the new mount API")
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>