IB: Fix typo in udev rule documentation

The proper syntax for udev rules is KERNEL==... instead of KERNEL=...

Signed-off-by: Bart Van Assche <bart.vanassche@gmail.com>
Reported-by: Lukasz Jurewicz <lukasz.jurewicz@gmail.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
diff --git a/Documentation/infiniband/user_mad.txt b/Documentation/infiniband/user_mad.txt
index 744687d..8a36695 100644
--- a/Documentation/infiniband/user_mad.txt
+++ b/Documentation/infiniband/user_mad.txt
@@ -128,8 +128,8 @@
   To create the appropriate character device files automatically with
   udev, a rule like
 
-    KERNEL="umad*", NAME="infiniband/%k"
-    KERNEL="issm*", NAME="infiniband/%k"
+    KERNEL=="umad*", NAME="infiniband/%k"
+    KERNEL=="issm*", NAME="infiniband/%k"
 
   can be used.  This will create device nodes named