iwlwifi: allocated rx page accounting cleanup

In iwlwifi, priv->alloc_rxb_page is used to keep track of the Rx
pages allocated by the driver. This cleans up the page free routines
by introducing __iwl_free_pages/iwl_free_pages so that the accounting
is more accurate and less error prone. This also fixes two instances where
the counter was not updated.

Signed-off-by: Zhu Yi <yi.zhu@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/iwlwifi/iwl-scan.c b/drivers/net/wireless/iwlwifi/iwl-scan.c
index a2b2b83..fa1c89b 100644
--- a/drivers/net/wireless/iwlwifi/iwl-scan.c
+++ b/drivers/net/wireless/iwlwifi/iwl-scan.c
@@ -144,8 +144,7 @@
 		clear_bit(STATUS_SCAN_HW, &priv->status);
 	}
 
-	priv->alloc_rxb_page--;
-	free_pages(cmd.reply_page, priv->hw_params.rx_page_order);
+	iwl_free_pages(priv, cmd.reply_page);
 
 	return ret;
 }