LU-8632 osc: remove of usage removed 'page_count' local variable

LU-8632 osc: remove of usage removed 'page_count' local variable

Address of function 'page_count' is used instead of a local variable
which was removed in commit 7f2aae8d80a73de7408668bbe569d5f4d8553efe.

Test-Parameters: trivial

Change-Id: I92626b27b21c291101299b52b46287262d27a4bd
Signed-off-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-on: http://review.whamcloud.com/22654
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Jinshan Xiong <jinshan.xiong@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>