RDMA: Move XRCD to be under ib_core responsibility

Update the code to allocate and free ib_xrcd structure in the
ib_core instead of inside drivers.

Link: https://lore.kernel.org/r/20200630101855.368895-4-leon@kernel.org
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/infiniband/hw/mlx5/main.c

@@ -6671,6 +6671,8 @@ static const struct ib_device_ops mlx5_ib_dev_mw_ops = {
 static const struct ib_device_ops mlx5_ib_dev_xrc_ops = {
 	.alloc_xrcd = mlx5_ib_alloc_xrcd,
 	.dealloc_xrcd = mlx5_ib_dealloc_xrcd,
+
+	INIT_RDMA_OBJ_SIZE(ib_xrcd, mlx5_ib_xrcd, ibxrcd),
 };
 
 static const struct ib_device_ops mlx5_ib_dev_dm_ops = {