IB/ipath: MAD performance sampling registers support

Add support for QLogic HCAs which have hardware performance sampling
registers for PortSamplesControl and PortSamplesResult MADs.

Signed-off-by: Ralph Campbell <ralph.campbell@qlogic.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
diff --git a/drivers/infiniband/hw/ipath/ipath_verbs.c b/drivers/infiniband/hw/ipath/ipath_verbs.c
index c4c9984..a2baa61 100644
--- a/drivers/infiniband/hw/ipath/ipath_verbs.c
+++ b/drivers/infiniband/hw/ipath/ipath_verbs.c
@@ -1641,6 +1641,7 @@
 		cntrs.local_link_integrity_errors;
 	idev->z_excessive_buffer_overrun_errors =
 		cntrs.excessive_buffer_overrun_errors;
+	idev->z_vl15_dropped = cntrs.vl15_dropped;
 
 	/*
 	 * The system image GUID is supposed to be the same for all