staging/lustre: fix LBUG and inode refcount bug

ldlm_proc_setup and ldlm_proc_cleanup should reset global
pde pointers otherwise remount may hit
LASSERT(ldlm_ns_proc_dir == NULL);

Also in libcfs_sock_ioctl, fput() includes itself sock_release.
So don't call sock_release twice otherwise kernel may oops
due to incorrect inode ref counting.

Signed-off-by: Peng Tao <tao.peng@emc.com>
Signed-off-by: Andreas Dilger <andreas.dilger@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>