staging/lustre/llite: make sure we do cl_page_clip on the last page

When we are doing a partial IO on both first and last page,
the logic currently only call cl_page_clip on the first page, which
will end up with a incorrect i_size.

Signed-off-by: Li Dongyang <dongyang.li@anu.edu.au>
Reviewed-on: http://review.whamcloud.com/11630
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-5552


Reviewed-by: Ian Costello <costello.ian@gmail.com>
Reviewed-by: Niu Yawei <yawei.niu@intel.com>
Reviewed-by: Li Xi <pkuelelixi@gmail.com>
Reviewed-by: Jinshan Xiong <jinshan.xiong@intel.com>
Signed-off-by: Oleg Drokin <green@linuxhacker.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>