libceph, ceph: move ceph_calc_file_object_mapping() to striper.c

ceph_calc_file_object_mapping() has nothing to do with osdmaps.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

include/linux/ceph/striper.h

@@ -7,6 +7,10 @@
 
 struct ceph_file_layout;
 
+void ceph_calc_file_object_mapping(struct ceph_file_layout *l,
+				   u64 off, u64 len,
+				   u64 *objno, u64 *objoff, u32 *xlen);
+
 struct ceph_object_extent {
 	struct list_head oe_item;
 	u64 oe_objno;