ceph: rename r_sent_stamp r_stamp

Make variable name slightly more generic, since it will (soon)
reflect either the time the request was sent OR the time it was
last determined to be still retrying.

Signed-off-by: Sage Weil <sage@newdream.net>
diff --git a/fs/ceph/osd_client.h b/fs/ceph/osd_client.h
index 1b1a3ca..b075991 100644
--- a/fs/ceph/osd_client.h
+++ b/fs/ceph/osd_client.h
@@ -70,7 +70,7 @@
 
 	char              r_oid[40];          /* object name */
 	int               r_oid_len;
-	unsigned long     r_sent_stamp;
+	unsigned long     r_stamp;            /* send OR check time */
 	bool              r_resend;           /* msg send failed, needs retry */
 
 	struct ceph_file_layout r_file_layout;