LU-4629 ldlm: fix uninitialized variable

'rc' might be used uninitialized in this function.

ldlm_lib.c:1902: 'rc' is declared.
ldlm_lib.c:1910: req->rq_export->exp_disconnected is false
ldlm_lib.c:1951: 'rc' is used, but is uninitialized.

Signed-off-by: Dmitry Eremin <dmitry.eremin@intel.com>
Change-Id: I0cea444d564f3806ed1d926ca5f4909f7005e240
Reviewed-on: http://review.whamcloud.com/10664
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Tested-by: Jenkins
Reviewed-by: James Simmons <uja.ornl@gmail.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>