staging/lustre/clio: collapse layer of cl_page

staging/lustre/clio: collapse layer of cl_page

Move radix tree to osc layer to for performance improvement.

Signed-off-by: Jinshan Xiong <jinshan.xiong@intel.com>
Reviewed-on: http://review.whamcloud.com/7892
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-3321
Reviewed-by: Lai Siyao <lai.siyao@intel.com>
Reviewed-by: Bobi Jam <bobijam@gmail.com>
Signed-off-by: Oleg Drokin <green@linuxhacker.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>