net_tstamp,doc: Add test program for SIOC{G,S}HWTSTAMP

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
diff --git a/Documentation/networking/timestamping/.gitignore b/Documentation/networking/timestamping/.gitignore
index 71e81eb..a380159 100644
--- a/Documentation/networking/timestamping/.gitignore
+++ b/Documentation/networking/timestamping/.gitignore
@@ -1 +1,2 @@
 timestamping
+hwtstamp_config