IB core: Add port_xmit_wait counter

Add the missing port_xmit_wait counter. This counter is displayed through
some tools like perfquery but is not available via sysfs.

For the PORT_PMA_ATTR macro the _counter field is set to zero
allowing us to specify the offset directly like with PORT_PMA_ATTR_EXT

See also the earlier work in 2008 by Vladimir Skolovsky

https://www.mail-archive.com/general@lists.openfabrics.org/msg20313.html

Signed-off-by: Vladimir Sokolvsky <vlad@mellanox.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/core/sysfs.c

@@ -530,6 +530,7 @@ static PORT_PMA_ATTR(port_xmit_data		    , 12, 32, 192);
 static PORT_PMA_ATTR(port_rcv_data		    , 13, 32, 224);
 static PORT_PMA_ATTR(port_xmit_packets		    , 14, 32, 256);
 static PORT_PMA_ATTR(port_rcv_packets		    , 15, 32, 288);
+static PORT_PMA_ATTR(port_xmit_wait		    ,  0, 32, 320);
 
 /*
  * Counters added by extended set
@@ -560,6 +561,7 @@ static struct attribute *pma_attrs[] = {
 	&port_pma_attr_port_rcv_data.attr.attr,
 	&port_pma_attr_port_xmit_packets.attr.attr,
 	&port_pma_attr_port_rcv_packets.attr.attr,
+	&port_pma_attr_port_xmit_wait.attr.attr,
 	NULL
 };
 
@@ -579,6 +581,7 @@ static struct attribute *pma_attrs_ext[] = {
 	&port_pma_attr_ext_port_xmit_data.attr.attr,
 	&port_pma_attr_ext_port_rcv_data.attr.attr,
 	&port_pma_attr_ext_port_xmit_packets.attr.attr,
+	&port_pma_attr_port_xmit_wait.attr.attr,
 	&port_pma_attr_ext_port_rcv_packets.attr.attr,
 	&port_pma_attr_ext_unicast_rcv_packets.attr.attr,
 	&port_pma_attr_ext_unicast_xmit_packets.attr.attr,
@@ -604,6 +607,7 @@ static struct attribute *pma_attrs_noietf[] = {
 	&port_pma_attr_ext_port_rcv_data.attr.attr,
 	&port_pma_attr_ext_port_xmit_packets.attr.attr,
 	&port_pma_attr_ext_port_rcv_packets.attr.attr,
+	&port_pma_attr_port_xmit_wait.attr.attr,
 	NULL
 };