net: dsa: ksz: ksz8795_spi_probe: fix possible NULL pointer dereference

Fix possible NULL pointer dereference in case devm_kzalloc() failed to
allocate memory

Fixes: cc13e52c3a ("net: dsa: microchip: Add Microchip KSZ8863 SPI based driver support")
Reported-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/dsa/microchip/ksz8795_spi.c

@@ -41,6 +41,9 @@ static int ksz8795_spi_probe(struct spi_device *spi)
 	int i, ret = 0;
 
 	ksz8 = devm_kzalloc(&spi->dev, sizeof(struct ksz8), GFP_KERNEL);
+	if (!ksz8)
+		return -ENOMEM;
+
 	ksz8->priv = spi;
 
 	dev = ksz_switch_alloc(&spi->dev, ksz8);