RDMA: Allow for NULL .modify_device() and .modify_port() methods

These methods don't make sense for iWARP devices, so rather than
forcing them to implement stubs, just return -ENOSYS in the core if
the hardware driver doesn't set .modify_device and/or .modify_port.

Signed-off-by: Roland Dreier <roland@purestorage.com>

drivers/infiniband/hw/cxgb3/iwch_provider.c

@@ -61,13 +61,6 @@
 #include "iwch_user.h"
 #include "common.h"
 
-static int iwch_modify_port(struct ib_device *ibdev,
-			    u8 port, int port_modify_mask,
-			    struct ib_port_modify *props)
-{
-	return -ENOSYS;
-}
-
 static struct ib_ah *iwch_ah_create(struct ib_pd *pd,
 				    struct ib_ah_attr *ah_attr)
 {
@@ -1392,7 +1385,6 @@ int iwch_register_device(struct iwch_dev *dev)
 	dev->ibdev.dma_device = &(dev->rdev.rnic_info.pdev->dev);
 	dev->ibdev.query_device = iwch_query_device;
 	dev->ibdev.query_port = iwch_query_port;
-	dev->ibdev.modify_port = iwch_modify_port;
 	dev->ibdev.query_pkey = iwch_query_pkey;
 	dev->ibdev.query_gid = iwch_query_gid;
 	dev->ibdev.alloc_ucontext = iwch_alloc_ucontext;