ceph: kill ceph_osdc_writepages() "flags" parameter

There is only one caller of ceph_osdc_writepages(), and it always
passes 0 as its "flags" argument.  Get rid of that argument and
replace its use in ceph_osdc_writepages() with 0.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
diff --git a/include/linux/ceph/osd_client.h b/include/linux/ceph/osd_client.h
index 7a63100..6540e88 100644
--- a/include/linux/ceph/osd_client.h
+++ b/include/linux/ceph/osd_client.h
@@ -274,8 +274,7 @@
 				u64 off, u64 len,
 				u32 truncate_seq, u64 truncate_size,
 				struct timespec *mtime,
-				struct page **pages, int nr_pages,
-				int flags);
+				struct page **pages, int nr_pages);
 
 /* watch/notify events */
 extern int ceph_osdc_create_event(struct ceph_osd_client *osdc,