drivers/net: use dev_get_drvdata

Eliminate direct accesses to the driver_data field.
cf 82ab13b26f15f49be45f15ccc96bfa0b81dfd015

The semantic patch that makes this change is as follows:
(http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@@
struct device *dev;
expression E;
type T;
@@

- dev->driver_data = (T)E
+ dev_set_drvdata(dev, E)

@@
struct device *dev;
type T;
@@

- (T)dev->driver_data
+ dev_get_drvdata(dev)
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
Acked-by: Zhu Yi <yi.zhu@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/iwlwifi/iwl-agn.c

@@ -2478,7 +2478,7 @@ static DEVICE_ATTR(power_level, S_IWUSR | S_IRUSR, show_power_level,
 static ssize_t show_qos(struct device *d,
 				struct device_attribute *attr, char *buf)
 {
-	struct iwl_priv *priv = (struct iwl_priv *)d->driver_data;
+	struct iwl_priv *priv = dev_get_drvdata(d);
 	char *p = buf;
 	int   q;