spi: spidev: Use "%u" to format __u32

On 64-bit with CONFIG_SPI_DEBUG=y and #define VERBOSE:

    drivers/spi/spidev.c:287:3: warning: format '%zd' expects argument of type 'signed size_t', but argument 4 has type '__u32' [-Wformat=]
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spidev.c

@@ -284,7 +284,7 @@ static int spidev_message(struct spidev_data *spidev,
 			k_tmp->speed_hz = spidev->speed_hz;
 #ifdef VERBOSE
 		dev_dbg(&spidev->spi->dev,
-			"  xfer len %zd %s%s%s%dbits %u usec %uHz\n",
+			"  xfer len %u %s%s%s%dbits %u usec %uHz\n",
 			u_tmp->len,
 			u_tmp->rx_buf ? "rx " : "",
 			u_tmp->tx_buf ? "tx " : "",