IB/ehca: Implement modify_port

Add "Modify Port" verb support to eHCA driver.  The IB communication
manager needs this to set the IsCM port capability bit when
initializing.

Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
diff --git a/drivers/infiniband/hw/ehca/ehca_main.c b/drivers/infiniband/hw/ehca/ehca_main.c
index 059da96..3b23d67 100644
--- a/drivers/infiniband/hw/ehca/ehca_main.c
+++ b/drivers/infiniband/hw/ehca/ehca_main.c
@@ -587,6 +587,7 @@
 		ehca_gen_err("Cannot allocate shca memory.");
 		return -ENOMEM;
 	}
+	mutex_init(&shca->modify_mutex);
 
 	shca->ibmebus_dev = dev;
 	shca->ipz_hca_handle.handle = *handle;