staging/lustre/llite: fix a flag bug of vvp_io_kernel_fault()

After vvp_io_kernel_fault() locked the page, it should set
VM_FAULT_LOCKED.

Signed-off-by: Li Xi <lixi@ddn.com>
Reviewed-on: http://review.whamcloud.com/10740


Reviewed-by: Jinshan Xiong <jinshan.xiong@intel.com>
Reviewed-by: Emoly Liu <emoly.liu@intel.com>
Signed-off-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>