drivers: soc: atmel: add null entry at the end of at91_soc_allowed_list[]

of_match_node() calls __of_match_node() which loops though the entries of
matches array. It stops when condition:
(matches->name[0] || matches->type[0] || matches->compatible[0]) is
false. Thus, add a null entry at the end of at91_soc_allowed_list[]
array.

Fixes: caab13b4 ("drivers: soc: atmel: Avoid calling at91_soc_init on non AT91 SoCs")
Cc: stable@vger.kernel.org #4.12+
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

drivers/soc/atmel/soc.c

@@ -275,7 +275,8 @@ static const struct of_device_id at91_soc_allowed_list[] __initconst = {
 	{ .compatible = "atmel,at91rm9200", },
 	{ .compatible = "atmel,at91sam9", },
 	{ .compatible = "atmel,sama5", },
-	{ .compatible = "atmel,samv7", }
+	{ .compatible = "atmel,samv7", },
+	{ }
 };
 
 static int __init atmel_soc_device_init(void)