IB/usnic: Remove unused variable in usnic_debugfs_exit()

The variable qp_grp is initialized but never used otherwise, so remove
the unused variable.

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Roland Dreier <roland@purestorage.com>

drivers/infiniband/hw/usnic/usnic_debugfs.c

@@ -131,13 +131,9 @@ void usnic_debugfs_exit(void)
 
 void usnic_debugfs_flow_add(struct usnic_ib_qp_grp_flow *qp_flow)
 {
-	struct usnic_ib_qp_grp *qp_grp;
-
 	if (IS_ERR_OR_NULL(flows_dentry))
 		return;
 
-	qp_grp = qp_flow->qp_grp;
-
 	scnprintf(qp_flow->dentry_name, sizeof(qp_flow->dentry_name),
 			"%u", qp_flow->flow->flow_id);
 	qp_flow->dbgfs_dentry = debugfs_create_file(qp_flow->dentry_name,