RDMA/bnxt_re: Fix max_qp_wrs reported

While creating qps, the driver adds one extra entry to the sq size passed
by the ULPs in order to avoid queue full condition.  When ULPs creates QPs
with max_qp_wr reported, driver creates QP with 1 more than the max_wqes
supported by HW. Create QP fails in this case. To avoid this error, reduce
1 entry in max_qp_wqes and report it to the stack.

Link: https://lore.kernel.org/r/1606741986-16477-1-git-send-email-selvin.xavier@broadcom.comSigned-off-by: Devesh Sharma <devesh.sharma@broadcom.com>
Signed-off-by: Selvin Xavier <selvin.xavier@broadcom.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/infiniband/hw/bnxt_re/qplib_sp.c

@@ -118,7 +118,7 @@ int bnxt_qplib_get_dev_attr(struct bnxt_qplib_rcfw *rcfw,
 	 * 128 WQEs needs to be reserved for the HW (8916). Prevent
 	 * reporting the max number
 	 */
-	attr->max_qp_wqes -= BNXT_QPLIB_RESERVED_QP_WRS;
+	attr->max_qp_wqes -= BNXT_QPLIB_RESERVED_QP_WRS + 1;
 	attr->max_qp_sges = bnxt_qplib_is_chip_gen_p5(rcfw->res->cctx) ?
 			    6 : sb->max_sge;
 	attr->max_cq = le32_to_cpu(sb->max_cq);