LU-1756 kernel: clean up lustre_compat25.h

LU-1756 kernel: clean up lustre_compat25.h

1. unused functions:
   mapping_has_pages(), ll_call_writepage(), __set_page_ll_data()
   ll_invalidate_inode_pages(), __set_page_ll_data()
   CheckWriteback(), KIOBUF_GET_BLOCKS()
2. rename ll_vfs_create to vfs_create
3. remove kdev_t related macros
4. move cfs_cleanup_group_info() to lustre_common.h
5. remove kiobuf
6. move ll_inode_blksize() to lustre_common.h
7. drop LL_RENAME_DOES_D_MOVE

Signed-off-by: Peng Tao <tao.peng@emc.com>
Change-Id: Ic5e29e399e70ccd04cbe1448f3c6cfc3a258289b
Reviewed-on: http://review.whamcloud.com/3686
Tested-by: Hudson
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>