[][kernel][common][eth][Fix Coverity scan warning]

[Description]
Fix Coverity scan warning.

Without this patch, the Coverity might detect "Unsigned compared against
0 issue" warning in the mtk_add_mux().

[Release-log]


Change-Id: I7a7c3c7707063a7a0fd1d6b2c9564d0f0b49be45
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/8061023
diff --git a/target/linux/mediatek/files-5.4/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/target/linux/mediatek/files-5.4/drivers/net/ethernet/mediatek/mtk_eth_soc.c
index 1b01406..1c1eb75 100644
--- a/target/linux/mediatek/files-5.4/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+++ b/target/linux/mediatek/files-5.4/drivers/net/ethernet/mediatek/mtk_eth_soc.c
@@ -4669,8 +4669,7 @@
 	const __be32 *_id = of_get_property(np, "reg", NULL);
 	struct device_node *child;
 	struct mtk_mux *mux;
-	unsigned int id;
-	int err;
+	int id, err;
 
 	if (!_id) {
 		dev_err(eth->dev, "missing attach mac id\n");