LU-1442 llite: cleanup if a page failed to add into cache

LU-1442 llite: cleanup if a page failed to add into cache

In lustre, we assume that a dirty page must be queued in osc cache
for writing. However, in vvp_io_commit_write(), if a page failed to
add into cache, page dirty flag isn't cleared this will cause the
page will never be added into cache again.

Signed-off-by: Jinshan Xiong <jinshan.xiong@whamcloud.com>
Change-Id: I1c132c6f1d4f5845682e51850eb895b292fc5f0d
Reviewed-on: http://review.whamcloud.com/3447
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Niu Yawei <niu@whamcloud.com>
Reviewed-by: Johann Lombardi <johann@whamcloud.com>