memory: jz4780_nemc: Fix potential NULL dereference in jz4780_nemc_probe()

platform_get_resource() may fail and return NULL, so we should
better check it's return value to avoid a NULL pointer dereference
a bit later in the code.

This is detected by Coccinelle semantic patch.

Fixes: 911a8882 ("memory: jz4780-nemc: driver for the NEMC on JZ4780 SoCs")
Signed-off-by: Zhang Changzhong <zhangchangzhong@huawei.com>
Acked-by: Paul Cercueil <paul@crapouillou.net>
Link: https://lore.kernel.org/r/1607070717-32880-1-git-send-email-zhangchangzhong@huawei.comSigned-off-by: Krzysztof Kozlowski <krzk@kernel.org>

drivers/memory/jz4780-nemc.c

@@ -291,6 +291,8 @@ static int jz4780_nemc_probe(struct platform_device *pdev)
 	nemc->dev = dev;
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -EINVAL;
 
 	/*
 	 * The driver currently only uses the registers up to offset