zd1211rw: make 'handle_rx_packet: invalid, small RX packet' message debug-only

This message is should be debug-only as it tells almost nothing useful. It also
happens very often and just floods logs.

Signed-off-by: Jussi Kivilinna <jussi.kivilinna@mbnet.fi>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/zd1211rw/zd_usb.c b/drivers/net/wireless/zd1211rw/zd_usb.c
index 631194d..621c2cc 100644
--- a/drivers/net/wireless/zd1211rw/zd_usb.c
+++ b/drivers/net/wireless/zd1211rw/zd_usb.c
@@ -579,8 +579,8 @@
 
 	if (length < sizeof(struct rx_length_info)) {
 		/* It's not a complete packet anyhow. */
-		printk("%s: invalid, small RX packet : %d\n",
-		       __func__, length);
+		dev_dbg_f(zd_usb_dev(usb), "invalid, small RX packet : %d\n",
+					   length);
 		return;
 	}
 	length_info = (struct rx_length_info *)