IB/mlx5: Remove set but not used variable

Remove 'del_mkey' variable that is set but not used.

Fixes: 534fd7aa ("IB/mlx5: Manage indirection mkey upon DEVX flow for ODP")
Signed-off-by: Kamal Heib <kamalheib1@gmail.com>
Acked-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/hw/mlx5/devx.c

@@ -1107,12 +1107,10 @@ static void devx_free_indirect_mkey(struct rcu_head *rcu)
 static void devx_cleanup_mkey(struct devx_obj *obj)
 {
 	struct mlx5_mkey_table *table = &obj->mdev->priv.mkey_table;
-	struct mlx5_core_mkey *del_mkey;
 	unsigned long flags;
 
 	write_lock_irqsave(&table->lock, flags);
-	del_mkey = radix_tree_delete(&table->tree,
-				     mlx5_base_mkey(obj->devx_mr.mmkey.key));
+	radix_tree_delete(&table->tree, mlx5_base_mkey(obj->devx_mr.mmkey.key));
 	write_unlock_irqrestore(&table->lock, flags);
 }