[PKTGEN]: Add try_to_freeze()

The pktgen module prevents suspend-to-disk.  Fix.
Acked-by: N"Michal Piotrowski" <michal.k.k.piotrowski@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/core/pktgen.c

@@ -129,6 +129,7 @@
 #include <linux/ioport.h>
 #include <linux/interrupt.h>
 #include <linux/capability.h>
+#include <linux/freezer.h>
 #include <linux/delay.h>
 #include <linux/timer.h>
 #include <linux/list.h>
@@ -3333,6 +3334,8 @@ static int pktgen_thread_worker(void *arg)
 			t->control &= ~(T_REMDEV);
 		}
 
+		try_to_freeze();
+
 		set_current_state(TASK_INTERRUPTIBLE);
 	}