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>

drivers/net/wireless/zd1211rw/zd_usb.c

@@ -579,8 +579,8 @@ static void handle_rx_packet(struct zd_usb *usb, const u8 *buffer,
 
 	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 *)