bgpd: fix using of two pointers for struct thread_master *

bgp is using both bm->master and master pointers interchangebly
for thread manipulation.  Since they are the same thing consolidate
to one pointer.

Signed-off-by: Donald Sharp <sharpd@cumulusnetworks.com>
diff --git a/bgpd/bgp_dump.c b/bgpd/bgp_dump.c
index a3c9526..3d88dee 100644
--- a/bgpd/bgp_dump.c
+++ b/bgpd/bgp_dump.c
@@ -156,13 +156,13 @@
 	  secs_into_day = tm->tm_sec + 60*tm->tm_min + 60*60*tm->tm_hour;
 	  interval = interval - secs_into_day % interval; /* always > 0 */
 	}
-      bgp_dump->t_interval = thread_add_timer (master, bgp_dump_interval_func, 
+      bgp_dump->t_interval = thread_add_timer (bm->master, bgp_dump_interval_func,
 					       bgp_dump, interval);
     }
   else
     {
       /* One-off dump: execute immediately, don't affect any scheduled dumps */
-      bgp_dump->t_interval = thread_add_event (master, bgp_dump_interval_func,
+      bgp_dump->t_interval = thread_add_event (bm->master, bgp_dump_interval_func,
 					       bgp_dump, 0);
     }