LU-5971 llite: move vvp_io functions to vvp_io.c

LU-5971 llite: move vvp_io functions to vvp_io.c

Move all vvp_io related functions from lustre/llite/lcommon_cl.c to
the sole file where they are used lustre/llite/vvp_io.c.

Signed-off-by: John L. Hammond <john.hammond@intel.com>
Change-Id: I5b7d9671a32aaff7a2ebce42b0f5ff10e2eeb4ab
Reviewed-on: http://review.whamcloud.com/13376
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Jinshan Xiong <jinshan.xiong@intel.com>
Reviewed-by: Bobi Jam <bobijam@hotmail.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>