RDMA/cxgb3: Use structs to describe the uABI instead of opencoding

Open coding a loose value is not acceptable for describing the uABI in
RDMA. Provide the missing struct.
Acked-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/hw/cxgb3/iwch_provider.c

@@ -440,7 +440,9 @@ static struct ib_pd *iwch_allocate_pd(struct ib_device *ibdev,
 	php->pdid = pdid;
 	php->rhp = rhp;
 	if (context) {
-		if (ib_copy_to_udata(udata, &php->pdid, sizeof (__u32))) {
+		struct iwch_alloc_pd_resp resp = {.pdid = php->pdid};
+
+		if (ib_copy_to_udata(udata, &resp, sizeof(resp))) {
 			iwch_deallocate_pd(&php->ibpd);
 			return ERR_PTR(-EFAULT);
 		}

include/uapi/rdma/cxgb3-abi.h

@@ -74,4 +74,9 @@ struct iwch_create_qp_resp {
 struct iwch_reg_user_mr_resp {
 	__u32 pbl_addr;
 };
+
+struct iwch_alloc_pd_resp {
+	__u32 pdid;
+};
+
 #endif /* CXGB3_ABI_USER_H */