Staging: lustre: remove unneeded variable

ldlm_lock_enqueue() always returns ELDLM_OK, no matter what happens, so
removed the unneeded variable that this value was being stored in and
just return the value itself.

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Cc: Oleg Drokin <oleg.drokin@intel.com>
Cc: Andreas Dilger <andreas.dilger@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>