staging: lustre: llite: Change readdir BRW metrics

To simplify the code, change the metrics from bytes to pages.

Signed-off-by: Andreas Dilger <andreas.dilger@intel.com>
Signed-off-by: Jinshan Xiong <jinshan.xiong@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-5034
Reviewed-on: http://review.whamcloud.com/10275


Reviewed-by: wangdi <di.wang@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>