serial: max310x: Fix to avoid potential NULL pointer dereference

BugLink: https://bugs.launchpad.net/bugs/1826212

commit 3a10e3dd upstream.

of_match_device can return a NULL pointer when matching device is not
found. This patch avoids a scenario causing NULL pointer derefernce.
Signed-off-by: Aditya Pakki <pakki001@umn.edu>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

drivers/tty/serial/max310x.c

@@ -1306,6 +1306,8 @@ static int max310x_spi_probe(struct spi_device *spi)
 	if (spi->dev.of_node) {
 		const struct of_device_id *of_id =
 			of_match_device(max310x_dt_ids, &spi->dev);
+		if (!of_id)
+			return -ENODEV;
 
 		devtype = (struct max310x_devtype *)of_id->data;
 	} else {