RDMA/cxgb4: Max fastreg depth depends on DSGL support

The max depth of a fastreg mr depends on whether the device supports
DSGL or not.  So compute it dynamically based on the device support
and the module use_dsgl option.

Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

drivers/infiniband/hw/cxgb4/qp.c

@@ -566,7 +566,8 @@ static int build_fastreg(struct t4_sq *sq, union t4_wr *wqe,
 	int pbllen = roundup(wr->wr.fast_reg.page_list_len * sizeof(u64), 32);
 	int rem;
 
-	if (wr->wr.fast_reg.page_list_len > T4_MAX_FR_DEPTH)
+	if (wr->wr.fast_reg.page_list_len >
+	    t4_max_fr_depth(use_dsgl))
 		return -EINVAL;
 
 	wqe->fr.qpbinde_to_dcacpu = 0;