staging/lustre/llite: remove llite proc root on init failure

In init_lustre_lite() ensure that /proc/fs/lustre/llite is removed in
case of failure. Generally rework the cleanup code in this function.

Signed-off-by: John L. Hammond <john.hammond@intel.com>
Reviewed-on: http://review.whamcloud.com/6420
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-3331


Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Reviewed-by: James Simmons <uja.ornl@gmail.com>
Signed-off-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>