ath: Add and use pr_fmt, convert printks to pr_<level>

Use a more current logging style.
Make sure all output is prefixed appropriately.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/main.c b/drivers/net/wireless/ath/main.c
index ea2c737..8e99540 100644
--- a/drivers/net/wireless/ath/main.c
+++ b/drivers/net/wireless/ath/main.c
@@ -14,6 +14,8 @@
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
 #include <linux/kernel.h>
 #include <linux/module.h>
 
@@ -49,7 +51,7 @@
 		if (off != 0)
 			skb_reserve(skb, common->cachelsz - off);
 	} else {
-		printk(KERN_ERR "skbuff alloc of size %u failed\n", len);
+		pr_err("skbuff alloc of size %u failed\n", len);
 		return NULL;
 	}