IB/ipath: Clean up some comments

Signed-off-by: Dave Olson <dave.olson@qlogic.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
diff --git a/drivers/infiniband/hw/ipath/ipath_keys.c b/drivers/infiniband/hw/ipath/ipath_keys.c
index 85a4aef..8f32b17 100644
--- a/drivers/infiniband/hw/ipath/ipath_keys.c
+++ b/drivers/infiniband/hw/ipath/ipath_keys.c
@@ -128,9 +128,8 @@
 	int ret;
 
 	/*
-	 * We use LKEY == zero to mean a physical kmalloc() address.
-	 * This is a bit of a hack since we rely on dma_map_single()
-	 * being reversible by calling bus_to_virt().
+	 * We use LKEY == zero for kernel virtual addresses
+	 * (see ipath_get_dma_mr and ipath_dma.c).
 	 */
 	if (sge->lkey == 0) {
 		struct ipath_pd *pd = to_ipd(qp->ibqp.pd);