LU-5613 lustre: unused variable in tgt_brw_read()

LU-5613 lustre: unused variable in tgt_brw_read()

Local variable niocount in tgt_brw_read() is assigned a value
but never used again, and thus can be removed.

Signed-off-by: Isaac Huang <he.huang@intel.com>
Change-Id: Ide032596e6877a7bc6d3cbd6eaf3cfd7e582eb23
Reviewed-on: http://review.whamcloud.com/11888
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Fan Yong <fan.yong@intel.com>
Reviewed-by: Mike Pershin <mike.pershin@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>