doc: fix checking socket() in net tstamp example

Signed-off-by: Ali Gholami Rudi <ali@rudi.ir>
Acked-by: Patrick Ohly <patrick.ohly@intel.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/Documentation/networking/timestamping/timestamping.c b/Documentation/networking/timestamping/timestamping.c
index a7936fe..bab619a 100644
--- a/Documentation/networking/timestamping/timestamping.c
+++ b/Documentation/networking/timestamping/timestamping.c
@@ -370,7 +370,7 @@
 	}
 
 	sock = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
-	if (socket < 0)
+	if (sock < 0)
 		bail("socket");
 
 	memset(&device, 0, sizeof(device));