[media] af9035: fix warning

On a 32 bit system:

af9035.c: In function 'af9035_download_firmware':
af9035.c:446:3: warning: format '%lu' expects argument of type 'long unsigned
int', but argument 3 has type 'unsigned int' [-Wformat]

%zu avoids any warning on both 32 and 64 bit systems.
Signed-off-by: Gianluca Gennari <gennarone@gmail.com>
Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/dvb/dvb-usb/af9035.c

@@ -440,7 +440,7 @@ static int af9035_download_firmware(struct usb_device *udev,
 
 		i -= hdr_data_len + HDR_SIZE;
 
-		pr_debug("%s: data uploaded=%lu\n", __func__, fw->size - i);
+		pr_debug("%s: data uploaded=%zu\n", __func__, fw->size - i);
 	}
 
 	/* firmware loaded, request boot */