tty: serial: max310x: Add terminating entry for spi_device_id table

The spi_device_id table is supposed to be zero-terminated.
Signed-off-by: Axel Lin <axel.lin@ingics.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/max310x.c

@@ -1239,6 +1239,7 @@ static int __devexit max310x_remove(struct spi_device *spi)
 static const struct spi_device_id max310x_id_table[] = {
 	{ "max3107",	MAX310X_TYPE_MAX3107 },
 	{ "max3108",	MAX310X_TYPE_MAX3108 },
+	{ }
 };
 MODULE_DEVICE_TABLE(spi, max310x_id_table);