raw1394: remove useless last_time

It seems to me this code is useless: removing it.

https://bugzilla.gnome.org/show_bug.cgi?id=618871
diff --git a/ext/raw1394/gst1394clock.c b/ext/raw1394/gst1394clock.c
index 6f1546a..b7d4a8f 100644
--- a/ext/raw1394/gst1394clock.c
+++ b/ext/raw1394/gst1394clock.c
@@ -82,7 +82,6 @@
 static void
 gst_1394_clock_init (Gst1394Clock * clock)
 {
-  clock->last_time = 0;
   GST_OBJECT_FLAG_SET (clock, GST_CLOCK_FLAG_CAN_SET_MASTER);
 }
 
diff --git a/ext/raw1394/gst1394clock.h b/ext/raw1394/gst1394clock.h
index 98150ff..ab7594d 100644
--- a/ext/raw1394/gst1394clock.h
+++ b/ext/raw1394/gst1394clock.h
@@ -58,7 +58,6 @@
 
   raw1394handle_t handle;
 
-  GstClockTime last_time;
   guint32 cycle_timer_lo;
   guint32 cycle_timer_hi;
 };