libceph: fix msgr keepalive flag

There was some broken keepalive code using a dead variable.  Shift to using
the proper bit flag.

Signed-off-by: Sage Weil <sage@newdream.net>

include/linux/ceph/messenger.h

@@ -161,7 +161,6 @@ struct ceph_connection {
 	struct list_head out_queue;
 	struct list_head out_sent;   /* sending or sent but unacked */
 	u64 out_seq;		     /* last message queued for send */
-	bool out_keepalive_pending;
 
 	u64 in_seq, in_seq_acked;  /* last message received, acked */