LU-3254 llite: Update layout_gen only if layout change succeed

LU-3254 llite: Update layout_gen only if layout change succeed

Move layout generation update to ll_layout_conf() so that it will
change layout at LLITE only if layout update has succeeded.

Signed-off-by: Jinshan Xiong <jinshan.xiong@intel.com>
Change-Id: I407d617be184b1c888d6b16b11f7e33bf10add80
Reviewed-on: http://review.whamcloud.com/9858
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Lai Siyao <lai.siyao@intel.com>
Reviewed-by: Bobi Jam <bobijam@gmail.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>