IB/mthca: Fix reserved MTTs calculation on mem-free HCAs

The reserved_mtts field has different meaning in Tavor and Arbel, so
we are wasting mtt entries on memfree. Fix the Arbel case to match
Tavor semantics.
Signed-off-by: Michael S. Tsirkin <mst@mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

drivers/infiniband/hw/mthca/mthca_cmd.c

@@ -1051,6 +1051,10 @@ int mthca_QUERY_DEV_LIM(struct mthca_dev *dev,
 	MTHCA_GET(field, outbox, QUERY_DEV_LIM_MAX_EQ_OFFSET);
 	dev_lim->max_eqs = 1 << (field & 0x7);
 	MTHCA_GET(field, outbox, QUERY_DEV_LIM_RSVD_MTT_OFFSET);
+	if (mthca_is_memfree(dev))
+		dev_lim->reserved_mtts = ALIGN((1 << (field >> 4)) * sizeof(u64),
+					       MTHCA_MTT_SEG_SIZE) / MTHCA_MTT_SEG_SIZE;
+	else
 		dev_lim->reserved_mtts = 1 << (field >> 4);
 	MTHCA_GET(field, outbox, QUERY_DEV_LIM_MAX_MRW_SZ_OFFSET);
 	dev_lim->max_mrw_sz = 1 << field;