LU-1994 llite: kernel 3.5 renames end_writeback to clear_inode

LU-1994 llite: kernel 3.5 renames end_writeback to clear_inode

kernel commit dbd5768f8 renames end_writeback to clear_inode,
which used to exist for ~2.6.36 kernels.

Signed-off-by: Peng Tao <tao.peng@emc.com>
Signed-off-by: yang sheng <ys@whamcloud.com>
Change-Id: I2435e820092085c0fb55539818f4bad9e48ff386
Reviewed-on: http://review.whamcloud.com/3756
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Yang Sheng <yang.sheng@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>