IB/core: Set hop limit in ib_init_ah_from_wc correctly

The hop_limit value in the ah_attr should be 0xFF, not the value read
from the received GRH (which should be 0).  See 13.5.4.4 in the 1.2 IB
spec.

Signed-off-by: Sean Hefty <sean.hefty@intel.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

drivers/infiniband/core/verbs.c

@@ -167,7 +167,7 @@ int ib_init_ah_from_wc(struct ib_device *device, u8 port_num, struct ib_wc *wc,
 		ah_attr->grh.sgid_index = (u8) gid_index;
 		flow_class = be32_to_cpu(grh->version_tclass_flow);
 		ah_attr->grh.flow_label = flow_class & 0xFFFFF;
-		ah_attr->grh.hop_limit = grh->hop_limit;
+		ah_attr->grh.hop_limit = 0xFF;
 		ah_attr->grh.traffic_class = (flow_class >> 20) & 0xFF;
 	}
 	return 0;