LU-5290 clio: reorder initialization in cl_req_alloc()

LU-5290 clio: reorder initialization in cl_req_alloc()

In cl_req_alloc() ensure that the list heads crq_pages and crq_layers
have been initialized before passing the request to
cl_req_completion(). This fixes an oops in the error path.

Signed-off-by: John L. Hammond <john.hammond@intel.com>
Change-Id: I1f4ff994ca5db974e97b41452f7351f68ed350f8
Reviewed-on: http://review.whamcloud.com/11009
Tested-by: Jenkins
Reviewed-by: Bobi Jam <bobijam@gmail.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Jinshan Xiong <jinshan.xiong@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>