npcm7xx: fix error handling in the emc driver

This fixes a kernel crash if the mac address is not set.

meta-nuvoton/recipes-kernel/linux/linux-nuvoton.inc

@@ -9,6 +9,7 @@ KCONFIG_MODE="--alldefconfig"
 KSRC ?= "git://github.com/openbmc/linux;protocol=git;branch=${KBRANCH}"
 SRC_URI = "${KSRC}"
 SRC_URI_append_npcm7xx = " file://defconfig"
+SRC_URI_append_npcm7xx = " file://npcm7xx_emc-is_err-fix.patch"
 
 LINUX_VERSION_EXTENSION ?= "-${SRCREV}"
 

meta-nuvoton/recipes-kernel/linux/linux-nuvoton/npcm7xx_emc-is_err-fix.patch

@@ -0,0 +1,28 @@
+From 95c9299759e5ddd71ccea042a27135aae44bbaaf Mon Sep 17 00:00:00 2001
+From: Havard Skinnemoen <hskinnemoen@google.com>
+Date: Fri, 10 Jul 2020 22:35:05 -0700
+Subject: [PATCH] npcm7xx_emc: Use IS_ERR instead of NULL check
+
+of_get_mac_address returns ERR_PTR on error, not NULL.
+
+Signed-off-by: Havard Skinnemoen <hskinnemoen@google.com>
+---
+ drivers/net/ethernet/nuvoton/npcm7xx_emc.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/drivers/net/ethernet/nuvoton/npcm7xx_emc.c b/drivers/net/ethernet/nuvoton/npcm7xx_emc.c
+index efb441d511c5..41c7f814a9c3 100644
+--- a/drivers/net/ethernet/nuvoton/npcm7xx_emc.c
++++ b/drivers/net/ethernet/nuvoton/npcm7xx_emc.c
+@@ -1753,7 +1753,7 @@ static void get_mac_address(struct net_device *dev)
+
+ 	mac_address = of_get_mac_address(np);
+
+-	if (mac_address != 0)
++	if (!IS_ERR(mac_address))
+ 		ether_addr_copy(dev->dev_addr, mac_address);
+
+ 	if (is_valid_ether_addr(dev->dev_addr)) {
+-- 
+2.27.0.383.g050319c2ae-goog
+