staging/lustre/llite: use vui prefix for struct vvp_io members

Rename members of struct vvp_io to used to start with vui_ rather than
cui_.  Rename several instances of struct vvp_io * from cio to vio.

Signed-off-by: John L. Hammond <john.hammond@intel.com>
Reviewed-on: http://review.whamcloud.com/13363
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-5971


Reviewed-by: Bobi Jam <bobijam@hotmail.com>
Reviewed-by: Lai Siyao <lai.siyao@intel.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>