staging/lustre:llite: remove struct ll_ra_read

staging/lustre:llite: remove struct ll_ra_read

Ever since removal of the the unused function ll_ra_read_get(),
the struct ll_ra_read members lrr_reader and lrr_linkage and
the struct ll_readahead_state member ras_read_beads unnecessary
so remove them.
In struct vvp_io replace the struct ll_ra_read cui_bead member with
cui_ra_start and cui_ra_count.

Signed-off-by: John L. Hammond <john.hammond@intel.com>
Reviewed-on: http://review.whamcloud.com/13347
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>